My kitchenaid stand mixer will not shut off, or will suddenly come back on at slightest movement. I have to unplug it to be sure I don't get hurt.

Make sure it's unplugged, remove and inspect the carbon brushes one at a time under those black screws on the side. They are keyed with one corner of the square ground off so will only go in properly one way so eyes open when you take them out. If they are less than 10mm long replace them. Next would be look under the back cover for a broken wire to the black square speed control plate. Broken wires are only likely to be one of the bottom 2 on either side. Any more testing is going to require a multimeter.

If nothing is sticking in the movement of the control plate at the back I would replace the little PCB at the back just above the control plate. Where I live it is called a phase board.

Solution for these KitchenAid Stand Mixer Models

• KitchenAid Stand Mixer Service Manual - K45SS
• KitchenAid Stand Mixer Service Manual - K5SS
• KitchenAid Stand Mixer Service Manual - KP50P
• KitchenAid Stand Mixer Service Manual - KSM50P
• KitchenAid Stand Mixer Service Manual - KPM5
• KitchenAid Stand Mixer Service Manual - KSM5
• KitchenAid Stand Mixer Service Manual - KPM50
• KitchenAid Stand Mixer Service Manual - KSM75
• KitchenAid Stand Mixer Service Manual - KSM90
• KitchenAid Stand Mixer Service Manual - KSM103
• KitchenAid Stand Mixer Service Manual - KSM110
• KitchenAid Stand Mixer Service Manual - KSM150
• KitchenAid Stand Mixer Service Manual - KSM151
• KitchenAid Stand Mixer Service Manual - KSM156
• KitchenAid Stand Mixer Service Manual - KSMC50

Fix KitchenAid Stand Mixer Workshop Service Repair Manual Download

Did you clean the are around the variable-speed control lever?

Please be sure to unplug the mixer BEFORE disassembling the mixer.

http://www.ereplacementparts.com/kitchenaid-k45sswh0-classic-stand-mixer-parts-c-114958_114959_115060.html?page=4

http://www.ereplacementparts.com/article/11983/How_to_Replace_the_Speed_Sensor_and_Control_Board_on_a_KitchenAid_Pro_6_Mixer.html

Something is amiss under the back cover, unplug it, remove the cover and have a look. You may need a meter to test thinks but you could just as easy find something by looking. Make sure looking and touching is done unplugged.

Get a copy of the Repair Part List for your model at Kitchenaid.com
Download a Copy of the Kitchenaid Service manual.

http://www.kitchenaidparts.be/centers/servicemanual/mixer.pdf

The Worm Gear (12) teeth was stripped and needs to be replaced.
The whole Worm Gear Assembly can be purchased on eBay for under
$15.00

This may be explained with the bowl assembly. Being a bowl lift mixer, please follow the following steps to make sure the bowl is being secured before mixing:

There are the bowl-holding arms on the left and right hand side of the mixer. You will place the bowl on these arms, securing it onto the pegs.

Also, take your fingertips and press down firmly at the back of the bowl where it is resting against the base. You will hear an audible click as the bowl secures down into a spring latch mechanism on the stand mixer base, allowing the mixing bowl to sit flush and secure.

How comfortable are you with electrical parts? With the mixer UNPLUGGED and the switch ON measure resistance between the (flat) plug pins. If it's infinite (no meter movement) which is to be expected, there is an open circuit. The switch could be open or the wire to the switch could be disconnected (improbable) or the motor could be burned out and open (not very probable).

Maybe you could take the switch to a shop and have it tested.

This is not really a solution, just step 1.

The speed of these mixers is controlled by a component inside of the unit known as a Hall Sensor. This part is simple to remove and install. Just contact your nearest kitchenaid parts supplier for this item. It will cost about $13.00.

Be sure to unplug your mixer before removing the cover. You will need a phillips head screwdriver. Once inside you will be able to unplug the hall sensor from the control panel and from the top of the driveshaft. good luck

Yes, First unplug the unit.On either sides of the mixer there are two black motor brush retainer screws. Carefully remove them paying attention to the motor brush keyed position.You will see that one side is keyed.Check to see if the brush is competely worn down,or possibly cracked ( replace ).Always reinstall brushes the same way they came out.This should solve the problem.