KSM90ER4 KitchenAid Mixer - Instructions

Dismantled the mixer, took photos, and re-assembled unit.

I had a sourdough batch get into the space where dough hook attaches and it got so stuck that nothing - not hot water baths, not pliers and screwdrivers got the dough hook released. I had to open up the mixer following partselect you tube instructions and replacing the parts. What was confusing to me at first is that my 45 year old mixer had an extra screw on top of the shaft that no longer is there for newer models. It took me longer than I am willing to admit to figure that the extra screw is not the result of me skimming the instructions - the original shaft and dough hook went to a friend who broke it attempting to disengage the two parts (the dough turned out to be a very strong form of glue!). The piece is working like new. I preferred the agitator shaft with a spring to hold the end piece tighter, but the new set up without a spring works just fine.

INSTALLED PHASE CONTROL BOARD AND SPEED CONTROL PLATE, BOTH AT SAME TIME
Your DYI video was helpful, especially holding the spring with a cloth. Also good for fine tuning to get the speed exact

I am not handy, but was able to follow this YouTube video and do this repair easily and successfully: https://www.youtube.com/watch?v=1QsgPIL9FpA

I did take the mixer apart first to verify that the worm gear was the issue, then ordered the part from you site. I received it quickly and was able to do the repair and get back to mixing in a few days!

watched how to repair

With a screw driver remove the screws holding the old base in place. With a flat head screw driver carefully pry and remove old mixer base. With 600 grit sandpaper clean and make smooth any burrs or rough spots in the mixer base recessed area. You can use some light grease and coat the outer edges of new mixer base and place in the now cleaned mixer base recessed area. The new base maybe a tight fit and not be fully seated in the recess. If a tight fit, place the piece of 2x4 piece of wood over the new part that is in the recess and carefully tap the base home using the sledge hammer. Check to see, if the base is fully seated. If not fully seated, tap again When fully seated replace the screws. You may have to adjust the height of the stand mixer head with mixer paddle attached for proper clearance between bowl and paddle. See your mixer manual for adjustment procedure

I did exactly what the PartSelect video demonstrated after watching other DIY videos on the Internet, thus I did not remove the stand which seemed like a little too much for a simple straight forward repair. This is the second time I have replaced this gear. The first time was about 10 years ago when the bakelite gear broke on a 30 year old KitchenAid K
-45. That mixer made hundreds of loaves of bread after grinding many pounds of wheat berries. The only reason we had to replace it was that it walked off the flour dusted counter and landed on its head when my wife had her back turned. Otherwise we would still be using it. :-)
Thanks for the excellent service and instructions.

Order the worm gear part number PS11748374.
Watch this video.
https://www.youtube.com/watch?v=VeCiivPt7hk

I would recommend two people if possible.

Found control backplate out of adjustment. Should be nominal 3/8".Broken speed control spring which attaches to backplate bottom.
I recommend Loctite Blue to complement locknut's when adjusting RPM of "Stir" speed

The shield works sufficiently. Note that the shield is not a continuous circle as shown in the picture. This actually can be an asset because it can be installed or disassembled without stopping the mixer of having to lift the head while running.

I took apart the mixer housing and removed all the screws. The most difficult part was the two pins that needed to be removed with a metal punch. They were in fairly tight. The mixer came apart pretty easily and it was obvious which part needed to be replaced as it was broken and missing teeth. After replacing the gear and applying new grease for smooth operation, I simply put it back together and it has worked like new ever since.

You tube has great instructions! I would suggest when you buy a part to let customer know that they need a food grade gear grease ordered to complete the reinstall of all gears and body parts!

I followed the instructional video linked to my email order confirmation. Partselect provided one of the best how-to videos I've ever seen. With the right tools, a little patience and the video, I had an outstanding repair experience.

Removed old one and replaced with new one.

Took each area apart. Replaced the gear and reassembled it.