Hi, the speed lever won't move. I have checked that the bowl is securely placed and adjusted the height of the beaters? Can you tell me what else might be the problem. I have only had the appliance for a few months.

The kitchenaid warranty is exactly 365 days from date of registration "No Questions Asked" on day 366 you have no warranty and you gotta pay.
Now the good news; first check the wall socket, I know it works but check it anyway. then check your plug, did you step on it while you were working on the machine? The plug often falls to the floor during work and can get underfoot, you may have broken the plug it'self. next you will need a parts list for your model from Kitchenaid's website.
http://www.kitchenaid.com/customer-service/manuals/
My first suggestion is to try a minor adjustment of the speed control switch, they often get out of sync when you do something to the machine. You can find several videos of this on the youtube site. "Adjusting the speed control switch on kitchenaid mixer"
If the two or one of the top 2 screws on the speed control switch move it can shut the machine down just like an on/off switch. Did you remove the back cover during your adjustments? Did you remove and replace the carbon brushes on the side of the machine while working on the machine? If you did you might have put them back in incorrectly, if you did they will also act a a shutoff switch. If you did not take them out then DON"T as there are four ways to put the brushes back in and only one way is correct and there are two brushes to deal with. Has work ever been performed on the mixer before? Because if all you did was to adjjust the beater height screw then nothing should have effected the normal operation of the mixer. So if there is anything that you did but did not include in your description of work you performed then please let us know. We strive to give accurate solutions but... as I am a KA tech I do not have any other solutions with out the machine in front of me. Just so you know you can fix this yourself.

Get a copy of the Repair Part List for your model at Kitchenaid.com
Download the following Kitchenaid Service Manual:
http://www.kitchenaidparts.be/centers/servicemanual/mixer.pdf

It covers several models including yours.
1. Check/Adjust the Flat Beater to Bowl Clearance:

Turn screw (A) SLIGHTLY counter clockwise (left) to raise the flat

beater or clockwise (right) to lower the flat beater
2. Check the Beater Shaft (Agitator Shaft) making sure the Retaining ring
is flushed with the surface of the Planetary Assembly
Constant Pulling and Removal of the beaters can cause the Agitator shaft to move
3. If the above two still don't solve your problem, follow the service manual
directions to disassemble the Planetary Assembly and check for loose screws

Hi ARADAM, you don’t provide the model number or say if you have a ‘tilt-head’ or a ‘bowl-lift' mixer, which would helpful, but you can easily download a PDF version of your Owners Manual from the KA website at: (http://www.kitchenaid.com/flash.cmd?/#/page/home).
Click on Customer Care>Locate Manuals& Guides> and enter the 6 character model number and select a file listed under Owners Manuals and save that file to your PC. You’ll need to have Adobe Reader to be able to open it. Turn to Page 11 and you will find the instructions for adjusting the mixer head height. I have extracted the instructions below:
Beater to Bowl Clearance
Your mixer is adjusted at the factory so that the flat beater just clears the bottom of the bowl. If for any reason, the flat beater hits the bottom of the bowl or is too far away from the bowl, clearance.
Tilt-Head models
• Unplug mixer.
• Lift motor head.

• Turn screw (A) SLIGHTLY counter clockwise (left) to raise flat beater or clockwise (right) to lower flat beater.
• Make adjustment with flat beater, so it just clears surface of bowl.
If you over adjust the screw, the bowl lock lever may not lock into place.

Bowl-Lift models
• Unplug mixer.
• Place bowl lift handle in down position.


• Turn screw (B) SLIGHTLY counter clockwise (left) to raise flat beater and clockwise (right) to lower flat beater.
•Make adjustments with flat beater, so it just clears surface of bowl.
If you find the adjustment screw missing, you’ll need to replace it. But now you’ll need
I hope this helps! –Howard, Burke, VA
If this solution has helped you, please rate it, thanks! - hslincoln

Hi TCMARTIN. This should be pretty easy to do by yourself the instructions for adjusting your beater to bowl clearance is in your Owners Manual. I you don’t have the original manual you can easily download a PDF version of your Owners Manual from the KA website: (http://www.kitchenaid.com/flash.cmd?/#/page/home).
Click on Customer Care>Locate Manuals& Guides> and enter the 6 character model number, in your case K$45SSW and select the file listed for your model that appears under Owners Manuals (2): K45SSWH-0.pdf (2730.37 KB) and save that file to your PC. Turn to Page 13 and you will find the instructions for adjusting the mixer head height. I have extracted the instructions below:
Beater to Bowl Clearance
Your mixer is adjusted at the factory so that the flat beater just clears the bottom of the bowl. If for any reason, the flat beater hits the bottom of the bowl or is too far away from the bowl, clearance
Tilt-Head models
• Unplug mixer.
• Lift motor head.

• Turn screw (A) SLIGHTLY counter clockwise (left) to raise flat beater or clockwise (right) to lower flat beater.
• Make adjustment with flat beater, so it just clears surface of bowl.
If you over adjust the screw, the bowl lock lever may not lock into place.
I hope this helps! – Howard, Burke, VA
If this solution has helped you, please rate it, thanks! - hslincoln

Hi LEDAVETTORI, you don’t provide the model number or say if you have a ‘tilt-head’ or a ‘bowl-lift' mixer, which would helpful, but you can easily download a PDF version of your Owners Manual from the KA website at: (http://www.kitchenaid.com/flash.cmd?/#/page/home).
Click on Customer Care>Locate Manuals& Guides> and enter the 6 character model number and select a file listed under Owners Manuals and save that file to your PC. You’ll need to have Adobe Reader to be able to open it. Turn to Page 11 and you will find the instructions for adjusting the mixer head height. I have extracted the instructions below:
Beater to Bowl Clearance
Your mixer is adjusted at the factory so that the flat beater just clears the bottom of the bowl. If for any reason, the flat beater hits the bottom of the bowl or is too far away from the bowl, clearance.
Tilt-Head models
• Unplug mixer.
• Lift motor head.
• Turn screw (A) SLIGHTLY counter clockwise (left) to raise flat beater or clockwise (right) to lower flat beater.
• Make adjustment with flat beater, so it just clears surface of bowl.
If you over adjust the screw, the bowl lock lever may not lock into place.

Bowl-Lift models
• Unplug mixer.
• Place bowl lift handle in down position.

• Turn screw (B) SLIGHTLY counter clockwise (left) to raise flat beater and clockwise (right) to lower flat beater. •Make adjustments with flat beater, so it just clears surface of bowl.
If you find the adjustment screw missing, you’ll need to replace it. But now you’ll need
I hope this helps! –Howard, Burke, VA
If this solution has helped you, please rate it, thanks! - hslincoln

Hi LEDAVETORI, you don’t provide the model number or say if you have a ‘tilt-head’ or a ‘bowl-lift' mixer, which would helpful, but you can easily download a PDF version of your Owners Manual from the KA website at: (http://www.kitchenaid.com/flash.cmd?/#/page/home).
Click on Customer Care>Locate Manuals& Guides> and enter the 6 character model number and select a file listed under Owners Manuals and save that file to your PC. You’ll need to have Adobe Reader to be able to open it. Turn to Page 11 and you will find the instructions for adjusting the mixer head height. I have extracted the instructions below:
Beater to Bowl Clearance
Your mixer is adjusted at the factory so that the flat beater just clears the bottom of the bowl. If for any reason, the flat beater hits the bottom of the bowl or is too far away from the bowl, clearance.
Tilt-Head models
• Unplug mixer.
• Lift motor head.

• Turn screw (A) SLIGHTLY counter clockwise (left) to raise flat beater or clockwise (right) to lower flat beater.
• Make adjustment with flat beater, so it just clears surface of bowl.
If you over adjust the screw, the bowl lock lever may not lock into place.

Bowl-Lift models
• Unplug mixer.
• Place bowl lift handle in down position.

• Turn screw (B) SLIGHTLY counter clockwise (left) to raise flat beater and clockwise (right) to lower flat beater.
•Make adjustments with flat beater, so it just clears surface of bowl.
If you find the adjustment screw missing, you’ll need to replace it. But now you’ll need
I hope this helps! –Howard, Burke, VA
If this solution has helped you, please rate it, thanks! - hslincoln

Hi, JAKELEGJEETE, You don’t say if you have a ‘tilt-head’ or a ‘bowl-lift' mixer, but you can easily download a PDF version of your Owners Manual from the KA website at: (http://www.kitchenaid.com/flash.cmd?/#/page/home).
Click on Customer Care>Locate Manuals& Guides> and enter the 6 character model number (in your case, use KSM5PS)and select the last file listed that appear under Owners Manuals: and save that file to your PC. You’ll need to have Adobe Reader to be able to open it. Turn to Page 11 and you will find the instructions for adjusting the Beater to Bowl Clearance. I have extracted the instructions below:
Beater to Bowl Clearance
Your mixer is adjusted at the factory so that the flat beater just clears the bottom of the bowl. If for any reason, the flat beater hits the bottom of the bowl or is too far away from the bowl, clearance.
Tilt-Head models
• Unplug mixer.
• Lift motor head.

• Turn screw (A) SLIGHTLY counter clockwise (left) to raise flat beater or clockwise (right) to lower flat beater.
• Make adjustment with flat beater, so it just clears surface of bowl.
If you over adjust the screw, the bowl lock lever may not lock into place.

Bowl-Lift models
• Unplug mixer.
• Place bowl lift handle in down position.

• Turn screw (B) SLIGHTLY counter clockwise (left) to raise flat beater and clockwise (right) to lower flat beater.
•Make adjustments with flat beater, so it just clears surface of bowl.
If you find the adjustment screw missing, you’ll need to replace it. But now you’ll need
I hope this helps! –Howard, Burke, VA
If this solution has helped you, please rate it, thanks! - hslincoln

Hi, KLOEHR, your beater will not lengthen by losing a screw. However, if you lost your Beater to Bowl Clearance adjustment screw, then it might appear that your beater had ‘grown’ because now the beater may be touching the bottom of your mixing bowl, where previously it had not. Simply said, the beater didn’t grow the mixer head drooped.
You don’t say if you have a ‘tilt-head’ or a ‘bowl-lift' mixer, but you can easily download a PDF version of your Owners Manual from the KA website at: (http://www.kitchenaid.com/flash.cmd?/#/page/home).
Click on Customer Care>Locate Manuals& Guides> and enter the 6 character model number (in your case, use KSM5PS)and select the last file listed that appear under Owners Manuals: KSM5PSWW0.pdf (2930.74 KB) and save that file to your PC. You’ll need to have Adobe Reader to be able to open it. Turn to Page 11 and you will find the instructions for adjusting the mixer head height. I have extracted the instructions below:
Beater to Bowl Clearance
Your mixer is adjusted at the factory so that the flat beater just clears the bottom of the bowl. If for any reason, the flat beater hits the bottom of the bowl or is too far away from the bowl, clearance.
Tilt-Head models
• Unplug mixer.
• Lift motor head.

• Turn screw (A) SLIGHTLY counter clockwise (left) to raise flat beater or clockwise (right) to lower flat beater.
• Make adjustment with flat beater, so it just clears surface of bowl.
If you over adjust the screw, the bowl lock lever may not lock into place.

Bowl-Lift models
• Unplug mixer.
• Place bowl lift handle in down position.

• Turn screw (B) SLIGHTLY counter clockwise (left) to raise flat beater and clockwise (right) to lower flat beater.
•Make adjustments with flat beater, so it just clears surface of bowl.
If you find the adjustment screw missing, you’ll need to replace it. But now you’ll need
I hope this helps! –Howard, Burke, VA
If this solution has helped you, please rate it, thanks! - hslincoln

Hi, LAHR, by the symptoms you describe it appears that it’s time to adjust your mixer’s "Beater to Bowl Clearance" adjustment screw, which should be a pretty easy to do by yourself.
The instructions for adjusting your beater to bowl clearance are located in your Owners Manual. If you don’t have the original manual you can easily download a PDF version of it from the KA website: (http://www.kitchenaid.com/flash.cmd?/#/page/home).
Click on Customer Care>Locate Manuals& Guides> and enter the 6 character model number, in your case KSM150 and select the file listed for your model that appears under Owners Manuals (66) KSM150PSER1.pdf (732.33 KB) and save that file to your PC. Turn to Page 14 and you will find the instructions for adjusting the mixer head height.
But to save you some time, I have extracted the instructions below:
Beater to Bowl Clearance
Your mixer is adjusted at the factory so that the flat beater just clears the bottom of the bowl. If for any reason, the flat beater hits the bottom of the bowl or is too far away from the bowl, clearance
Tilt-Head models
• Unplug mixer.
• Lift motor head.

• Turn screw (A) SLIGHTLY counter clockwise (left) to raise flat beater or clockwise (right) to lower flat beater.
• Make adjustment with flat beater, so it just clears surface of bowl.
If you over adjust the screw, the bowl lock lever may not lock into place.
I hope this helps! – Howard, Burke, VA
If this solution has helped you, please rate it, thanks! - hslincoln

Hi KELLYSERMAN, this should be pretty easy to do by yourself the instructions for adjusting your beater to bowl clearance is in your Owners Manual. I you don’t have the original manual you can easily download a PDF version of your Owners Manual from the KA website: (http://www.kitchenaid.com/flash.cmd?/#/page/home).
Click on Customer Care>Locate Manuals& Guides> and enter the 6 character model number, in your case KSM150 and select the file listed for your model that appears under Owners Manuals (66): KSM150PSER1 (732.33KB) and save that file to your PC. Turn to Page 14 and you will find the instructions for adjusting the mixer head height. I have extracted the instructions below:
Beater to Bowl Clearance
Your mixer is adjusted at the factory so that the flat beater just clears the bottom of the bowl. If for any reason, the flat beater hits the bottom of the bowl or is too far away from the bowl, clearance
Tilt-Head models
• Unplug mixer.
• Lift motor head.

• Turn screw (A) SLIGHTLY counter clockwise (left) to raise flat beater or clockwise (right) to lower flat beater.
• Make adjustment with flat beater, so it just clears surface of bowl.
If you over adjust the screw, the bowl lock lever may not lock into place.
I hope this helps! – Howard, Burke, VA
If this solution has helped you, please rate it, thanks! - hslincoln