My girlfriends' stand mixer failed when the accessory drive cap fell into the mixing bowl and jambed the beater, spliting the worm gear. The teeth on this gear are made of nylon and are molded to an aluminum center. This part is designed to fail in situations like this, saving the more expensive transmission parts. Following a repair manual I found online, I first removed the rear cover and pulled out the cord strain relief out from the base. Next I removed the drip cup from around the base of the planetary drive. I then used a pin punch to drive out the pin holding the planetary to the center shaft and removed the planetary. The unit was then inverted and I removed 4 screws holding the bottom cover to the gear case, and the 5 screws from around the planetary drive. The bottom cover was then lifted off. Three screws holding the worm gear bracket in place were then removed and the worm gear assembly lifted out. A small pin holds the worm gear to the shaft. I drove this out with a small pin punch and the shaft and worm gear were then removed. There is also a thrust washer on this shaft, and it's location is important. Make a note for re-assembly. The new gear was installed and the entire process reversed for re-assembly. A successful repair completed! My girlfriend would have replaced this $200 appliance, but I was able to repair it for less than $30 including shipping.
I removed screws in a sequence that I felt wouldn't further damage the mixer until I had it completely unassembled. When I found the broken worm gear, I went online to find a part. I found an exploded view, but the part numbering was old, and the salesperson couldn't tell me what the worm gear and bracket assembly consisted of, as I only wanted the worm gear. After trying to drive the pin out of the assembly, and failing, I decided to back online and see if anyone else had a photo of the assembly. Luckily (and wisely) PartSelect,com did and that answered any questions I had. The price was better, too. Reassembly of the mixer was a cinch with the exploded view. It's working like new, and we're hoping for another 35 years of service from it! Thanks.
This was my husband's first time to taking apart any mixer - much less a heavy duty KitchenAid. Since we could not find a local repairman, the only thing to do was try to repair it himself. Using your exploded view of the machine he found on the internet, he ordered a gasket which he felt would be needed to repair the mixer. When he tore the machine down, the problem was what he had suspected - original grease had liquified and the rest had turned black in color. He went to a local auto parts store and bought a can of wheel bearing grease. He cleaned out the old oil and repacked with about a half pound of the new grease. The most difficult part of the repair was inserting the roll pin to attach the ring gear housing to the output shaft. It was impossible for him to reinsert the original pin, so he bought a new tension pin with which he was able to work. The only part he has been unable to align is the lever to lock/unlock the machine. He managed to set it enough that it locks when the lever is pushed halfway. The machine works great but I would not advise a person without any mechanical ability to try to repair these mixers.