The flat beater is stuck in the mixer and I can't remove it.

Push up and twist at the same time.

I had this happen on my Kitchen Aid mixer. There is probably a build up of dough/cake mix etc inside the hole where the beater fits into. Fill a mixing bowl or a jug deep enough to fit over beater with very hot or boiling water. Immerse the stuck beater in the water up to where it connects in to the mixer and hold for about minute. Once the hot water has melted the build up you should be able to remove the beater. Hopefully this may work on your brand of mixer.

Do you mean the beater is not touching the bottom of the bowl? AS in there is a gap between the beater and the bottom of the bowl so it is not mixing all the ingriedients?
If you have a Tilt-head style mixer, you can adjust the beater/bowl clearance by turning out the adjusting screw. Place your bowl on the bowl screw cap, Place the flat beater on the agitator shaft and lower the head of the mixer so the beater is at the bottom of the bowl. There should be a 1/16" clearance between the bowl and the beater, if the beater is too close to the bowl turn in the adjusting screw, and if the beater is too far away turn out the adjusting screw. The adjusting screw can be located by tilting the head of the mixer back, and in the neck of the mixer you will see a flat head adjusting screw.
However if you have a bowl lift mixer and the bowl is too far from the mixer there are a few different way to fix that problem. If the bowl and beater are too far apart start by adjusting the adjustment screw. On this mixer the adjustment screw is under the head. Remove the bowl, and beater and lay the mixer on its back. You should be able to see under the head a screw sticking out, it does not have a head, but a little slot in the screw, use a flat head screw and adjust the beat 1/4 turn. Put the beater and bowl back on and test mixer to see if it the beater has a 1/16" clearance. If it doesn't adjust the screw and 1/4 turn. If after adjusting the screw the beater and bowl still have too much clearance use a mallet and tap both sides of the yoke arm up evenly until 1/16" beater to bowl clearance is met.
You can use the same dime test in the bowl to make sure you have the correct 1/16" measurement for the beater/bowl distance.
Thank you,
Colleen
MendingShed.com
800-339-9297

Make sure your Beater can slip in and out of the Beater Shaft
easily. Do not force the beater onto the Shaft if the shaft is bent.
If it cannot be removed easily by hand, use a soft rubber mallet
(not a steel hammer) to slightly tap the beater so it can be moved
up and down the shaft or from side to side. Then you can easily
turn the beater left and remove it from the shaft.

From Kitchenaid Manual:
To Attach Flat Beater, Wire Whip, or Dough Hook
1. Turn speed control to OFF.
2. Unplug stand mixer or disconnect power.
3. Tilt motor head back.
4. Slip beater onto beater shaft and press upward
as far as possible.
5. Turn beater to right, hooking beater over pin on shaft.
6. Plug into a grounded 3 prong outlet.

To Remove Flat Beater, Wire Whip or Dough Hook
1. Turn speed control to OFF.
2. Unplug stand mixer or disconnect power.
3. Tilt motor head back.
4. Press beater upward as far as possible and turn left.
5. Pull beater from beater shaft

Make sure your Beater can slip in and out of the Beater Shaft

easily. Do not force the beater onto the Shaft if the shaft is bent.

If it cannot be removed easily by hand, use a soft rubber mallet

(not a steel hammer) to slightly tap the beater so it can be moved

up and down the shaft or from side to side. Then you can easily

turn the beater left and remove it from the shaft.

From Kitchenaid Manual:

To Attach Flat Beater, Wire Whip, or Dough Hook

1. Turn speed control to OFF.

2. Unplug stand mixer or disconnect power.

3. Tilt motor head back.

4. Slip beater onto beater shaft and press upward

as far as possible.

5. Turn beater to right, hooking beater over pin on shaft.

6. Plug into a grounded 3 prong outlet.

To Remove Flat Beater, Wire Whip or Dough Hook

1. Turn speed control to OFF.

2. Unplug stand mixer or disconnect power.

3. Tilt motor head back.

4. Press beater upward as far as possible and turn left.
5. Pull beater from beater shaft.

Make sure your Beater can slip in and out of the Beater Shaft
easily. Do not force the beater onto the Shaft if the shaft is bent.
If it cannot be removed easily by hand, use a soft rubber mallet
(not a steel hammer) to slightly tap the beater so it can be moved
up and down the shaft or from side to side. Then you can easily
turn the beater left and remove it from the shaft.

From Kitchenaid Manual:
To Attach Flat Beater, Wire Whip, or Dough Hook
1. Turn speed control to OFF.
2. Unplug stand mixer or disconnect power.
3. Tilt motor head back.
4. Slip beater onto beater shaft and press upward
as far as possible.
5. Turn beater to right, hooking beater over pin on shaft.
6. Plug into a grounded 3 prong outlet.

To Remove Flat Beater, Wire Whip or Dough Hook
1. Turn speed control to OFF.
2. Unplug stand mixer or disconnect power.
3. Tilt motor head back.
4. Press beater upward as far as possible and turn left.
5. Pull beater from beater shaft

Try some oil... ...or liquid dish detergent on a wet rag and rub around that area..

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

I contact Wolfgang Puck directly. Thanks

I had this happen today. I took a towel and covered all of the beater except where it attaches. I sprayed WD-40 on it. This loosened it and it came unstuck. Then I washed it thoroughly with hot water and soap. It had some dried batter stuck inside which caused it to stick. Guess I better pay better attention to how clean I get it inside. PS Don't spray WD-40 anywhere else - this is something you make food with!