Kitchenaid mixer K45SS only has one speed, slow. Have taken apart and regreased the machine. I plugged it in while the planetary head was off and it went through the speeds as normal, but as soon as

SOURCE: Kitchenaid Mixer K45SS

I just did this last week!
1 Unplug Mixer 2 Remove screw on TOP of mixer body, at back. 3 Remove rear cover and paper-gasket thing (its not the end of  the world if you end up tearing it a little). 4 the phase control (little circuit board w/wires) is at the top (you  should see it very easily) held on by one screw, remove it. 5 when the circuit board is unscrewed, disconnect all the wires  that are connected FROM THE CIRCUIT BOARD to the  black control plate (NOT all wires-there should be 4 left on  the control plate at this point).  you don't need to  remember where all the colors go as the control plate is  labeled->but looking at them and making sure you  understand the abbreviations would be beneficial  (BK=black, BL=Blue RW=Red&White W=white R=red etc.   6 install new phase control (screw), either buy new thermal  grease (used to keep the board cool->it transfers heat to  the mixer's housing) or try to salvage what you can from  the old one. 7 connect wires, paying attention to labels. 8 reinstall paper gasket, then cover, then screw to hold on back- cover.

SOURCE: kitchenaid mixer k45ss slow gear

If you look into the brush holder you will see a stopper at the botom ,(this is so when brushes are wore the spring is not driven into armature) .. the brushes have to be inserted so the groove is lined up , try that

SOURCE: Kitchenaid K5A mixer 10 speed only runs on fast, no slow speed

Pull the back off and there will be two screws at the top of the Speed Control Plate and a 3rd screw at the bottom. Tighten the top two screws down. [email protected]. Let me know if it works.

SOURCE: kitchenaid mixer speed

I would recommend that you first check the Hall Effect sensor which determines the mixer’s speed.  I had this exact problem and I actually went out and bought another Hall sensor for about $13.  I replaced the original sensor and made sure that the connection between the sensor and control board was nice and snug. My mixer worked as good as new! But I was curious to know if my original sensor was defective, so I put it back in mixer and again made sure all of the connections were snug and tight. Guess what?  My original sensor also made my mixer work!  There was nothing wrong with the original Hall Effect sensor except that the connection between the control board and sensor was not tight--unfortunately I didn't check the connection before I decided to buy another sensor. My guess is that the connection between the control board and the sensor probably loosens or comes undone over time from use and vibrations. To fix your problem:
1.  Download the mixer parts and diagrams from the Kitchenaid website to see what the Hall Effect sensor looks like. BTW the part number is 9703312.
2.  You'll need a phillips head screwdriver to open up the mixer gear case cover.
3.  Make sure that the connection between the control board and sensor is absolutely tight and snug.
4.  Also, make sure that the orientation of the sensor is correct.  It's difficult to tell which way the sensor should be connected because the control board has three prongs and the sensor can attach facing up or down. After you've made the connection, run the mixer. If it still doesn't work, disconnect the sensor, reconnect it with the prongs facing the opposite direction and try it again.  I actually found the right sensor orientation through a little trial and error.  But by going through this trial and error, I also had my Eureka moment when I realized that the original sensor probably would also work if it were reconnected with correct orientation.  
5.  This whole process probably takes about 10-15 minutes to perform.
6.  Finally, use your common sense and make sure to unplug the mixer before checking, connecting or disconnecting anything.

SOURCE: The kitchenaid speed lever is bent and jammed

Hi TIMDEIST, I hate it when you drop your mixer... they’re really not designed for gravity testing. Let’s see what you can do to get it fixed and operable again. The good news is that this can be fixed quite easily (OK, maybe a little effort) by yourself, if you are a DITY type person, feel adventurous, and your mixer is not under warranty. Be sure you have the Parts List manual on hand. If you're lacking one, you can download a PDF version from the KA website at: http://www.kitchenaid.com/flash.cmd?/#/page/home.
Click on Customer Care>Locate Manuals& Guides> then enter the visitor type “Consumer” and enter the 6 character model number, in this case K45SSW, and then select the file under Parts List (1) K45SSWH0.pdf (341.41 KB) (definitely check to see it this matches your mixer).
Although not providing step by step instructions, the Parts List manual provides an exploded view of the various component assemblies allowing you to see how the mixer all fits together. It is helpful for the disassembly, troubleshooting, and reassembly of your mixer.
Turn to pages 6 & 7, titled “Motor And Control Parts”, and locate Ill. Nos. 1, 2, 3, & 4. #3 is your Switch Lever and stud. If you can’t straighten it out then you will need to replace it. It might also be a good idea to check and see if anything else might be out of alignment due to the sudden stop when it was dropped.
As far as parts go, here are five potential vendors in no particular order: RepairClinic.com; mendingshed.com; searspartsdirect.com; partstore.com; and Grainger.com (for grease). Prices can vary widely between vendors, so do some comparison shopping. Here are some links to several excellent websites that detail the disassembling/greasing and reassembly of a KA Mixer.
Finally, here are some links to several excellent websites that detail the disassembling/reassembly of a KA Mixer.

• http://www.artisanbreadbaking.com/discussions/kitchen-aid.htm
• http://www.neilcrockett.com/mixer.htm
• http://www.foodonthefood.com/food_on_the_food/2009/04/how-to-repair-a-kitchenaid-mixer-yourself.html