Model K5SS -- The speed control lever will not stay in the slowest position - STIR - but will pop over to the next position - 2. Can I adjust anything to fix this problem?

it is most likely the armature. You can test the coils with a meter set to ohms. http://www.appliancepartspros.com/motor-control-parts-for-whirlpool-k5ss.html

The starting position for those top speed control plate screws with the lock nuts it 8 full turns in when you fit the plate. Correct adjustment begins in or out from that point. The bottom screw should have been left where it was to start with as that is for adjusting the start position so that when the lever closes the switch contacts to start the mixer the plate only starts moving when the lever moves to the second click. Try and get the bottom one roughly right and then work on the top ones. Turn it to the first click on the speed lever and then EVENLY adjust the 2 top screws to have the planetary turn 13 to 15 times per 15 seconds. Lock up the lock nuts and then check that the bottom screw is in the correct position with speed increasing a small amount as the lever slips into the second click.

Ideally you need to fix what's bent and that normally would involve splitting the cases to get at and repair or change the speed control lever. If you don't want to do that then removing the back cover and altering the adjustments and maybe bending the switch contacts may make it operate at both ends of the speed control.

There is a screw at the bottom of the motor head (flat head) you usually can't see it because of the top rim of the mixing bowl. hard to see and hard to reach, it may also be hard to turn due to "gunk" from mixing stuff (egg butter flour sugar) turn the screw counter clockwise to lower the motor head clockwise to raise it, you may also have the wrong size beater, it is not an uncommon problem, if you are the original owner and you have the original beater it should fix your problem with the adjusting screw, however I am not clear as to your model a 5SSWH would actually be a K5SSWH, which stands for kitchenaid 5 quart solid state white mixer, if this is your model number and you have the correct beater size then the adjusting screw will work to lower the head down, adjust it down using the stir or slowest speed just untill you can hear the beater "Ding" against the bottom of the bowl, then back it off a quarter turn to adjust properly. Hope this helps, let us know

First congrats on the great mixer that you have. next the pro 6 or professional 600 series mixers are of an entirely different design than the one that you have even though they are both bowl lift. Do you really need 6 quarts capacity? The pro series is a 575 watt mixer BTW, and it will have more power available to you IF you are doing bread or a lot of food grinding, if that is a requirement that you have then the 6 / 600 series is the better suited mixer but if all you are doing is general medium to light mixing duties then fix and keep the K5SS it a great machine,

Speed control plate at the back is stuck in the high position or you need a new phase board. That's the small PCB under the back cover at the top.

The K5SS is very similar to the 5-QT Artisan KSM150.
You need to adjust the mixer speeds. Obtain a copy of the K5SS Repair Part List from Kitchenaid.com. Remove the screw holding the End Cover and locate the three screws from the Control Plate. All three (2 top left and right, and 1 bottom) must all be adjusted. 1. Loosen the lock nuts enough & Turn the 2 top screws clockwise until they cannot be turned
anymore. Leave the bottom screw alone for now.
2. Use a dab of white paint or paper whiteout to mark the positions of the Phillips screws.
3. Plug in your mixer and Set the speed selector to "Stir".
4. Turn each top screw One full turn couterclockwise (alternating between Left and Right)
Keep making one full turn at the time (for both left and right) until the motor starts running.
5. Put your hand near the Agitator shaft and allow it to brush your finger slightly. Use your
watch or clock and start counting the number of times the shaft touches your finger in
60 seconds. The correct count should be 60 RPM (Rounds Per Minute). If it is less
or more than 60, give each screw 1/4 turn counterclockwise or clockwise and start counting
again. Now tighten both lock nuts.
6. Set the speed selector to "6" and turn the bottom screw either clockwise or counterclockwise
to achieve a speed of 180 RPM.

For your reference, the planetary RPM's for the 5-qt. tilt-head Artisan Stand Mixer are as follows:
Stir speed - 60
Speed 2 - 95
Speed 4 - 135
Speed 6 - 180
Speed 8 - 225
Speed 10 - 280

It looks like you may have two different problems. First, you must adjust the mixer speeds.
Second, if the motor runs at different speeds but the Planetary Assembly does not rotate, then
you may have a stripped Worm Gear Follower.
The K5SS is very similar to the 5-qt. tilt-head Artisan Stand Mixer.
You need to adjust the mixer speeds. Obtain a copy of the K5SS Repair Part List from Kitchenaid.com. Remove the screw holding the End Cover and locate the three screws from the Control Plate. All three (2 top left and right, and 1 bottom) must all be adjusted. 1. Loosen the lock nuts enough & Turn the 2 top screws clockwise until they cannot be turned
anymore. Leave the bottom screw alone for now.
2. Use a dab of white paint or paper whiteout to mark the positions of the Phillips screws.
3. Plug in your mixer and Set the speed selector to "Stir".
4. Turn each top screw One full turn couterclockwise (alternating between Left and Right)
Keep making one full turn at the time (for both left and right) until the motor starts running.
5. Put your hand near the Agitator shaft and allow it to brush your finger slightly. Use your
watch or clock and start counting the number of times the shaft touches your finger in
60 seconds. The correct count should be 60 RPM (Rounds Per Minute). If it is less
or more than 60, give each screw 1/4 turn counterclockwise or clockwise and start counting
again. Now tighten both lock nuts.
6. Set the speed selector to "6" and turn the bottom screw either clockwise or counterclockwise
to achieve a speed of 180 RPM.

For your reference, the planetary RPM's for the 5-qt. tilt-head Artisan Stand Mixer are as follows:
Stir speed - 60
Speed 2 - 95
Speed 4 - 135
Speed 6 - 180
Speed 8 - 225
Speed 10 - 280

There is a spring, item #4, which hooks on to the bottom of the control plate, item # 25, and pulls it back when you move the lever to off. Remove the rear cover and see if that spring is still connected to the control plate and to the lever arm, Item # 3. Here is the diagram:

http://shared.whirlpoolcorp.com/assets/pdfs/literature/Repair%20Part%20List%20-%208212369.pdf

Hi Burt. Go to mendingshed.com, look up kitchenaid mixer parts. Near the top of the page, locate the free kitchenaid service manual. Download this valuable manual, it will help you to diagnose and repair your mixer. Mending Shed also sells KA parts. If you order parts directly from kitchenaid be prepared to wait for at least a month for the parts to arrive.

If this solution has assisted you, please rate it. Good luck! ricardok45