It's a dirty job, but someone's got to do it. Fixing a KitchenAid stand mixer yourself will save you hundreds of dollars, and get your old mixer working like new. Even if it's a newer KitchenAid mixer more prone to malfunction than the old ones, it's fixable to a better state with just a little care and effort...if the mixer has not already fried itself. There was a solid reputation behind old KitchenAid stand mixers built on reliability, and it can still be true with a bit of do-it-yourself work.
The Attachment Hub
Wrap the mixer's wall plug in a plastic bag. Affix the baggie with a rubber band. This is a safety measure to ensure that there's no accidental starting of the mixer, and that no grease gets on the plug.
Remove the silver ring that encircles the planetary housing. This is called the drip cup. Use a small flat screwdriver on the top lip of the drip cup to loosen and remove it.
Lay the mixer on its side or turn it upside down. This gives better access to the screws that need to be removed for repair. Put a cloth or towel under the mixer to protect it.
Punch out the groove pin that holds the planetary gear assembly to the center shaft. Use a 5/32" punch. Then ease the planetary gear cover down and off the shaft using two flat screwdrivers.
Unscrew and remove the five screws on the perimeter of the exposed gear assembly.
Unscrew and remove the large screws that secure the top portion of the mixer to the base. There are four screws; use a large Phillips screwdriver. Note: the stand has to be removed from the top portion of the bowl-lift mixer models to access the two rear screws.
Remove the attachment hub bevel gear from the gear case. This bevel gear can be pulled out of the hub. Check it for wear or missing teeth.
Remove any old grease from the gear case. Pack the gear case with six ounces of new grease before reassembling the mixer.
The Planetary Assembly
Remove the three Phillips head screws from the worm gear assembly that hold it to the bottom half of the top housing. Lift it out of the mixer section.
Check the worm gear, and check the shaft and pinion for wear. The pinion has 11 teeth on the K45SS models (the one with a hinged top half); 10 teeth on all bowl-lift models.
Punch out the groove pin to free the gears for replacement if necessary.
Reassemble the worm gear, shaft and pinion of the gear assembly (if it's been disassembled), being sure to replace the fiber washers where they originally were located.
Position the worm gear assembly and bearing bracket on the gear case bottom cover. Two dowels fit into the base. Firmly tighten the three screws that secure the bearing bracket.
Reattach the top and bottom planetary sections. Carefully line up the shaft in the upper gear housing. The pieces assemble easily if correctly positioned.
Attach the circular internal gear to the gear case cover. Align the notches with the screw holes in the gear case, and screw in the five screws to lock it in place. .
Pack the area of the internal gear with new grease.
Line up the two halves of the mixer top, and screw in the four large Fillister screws.
Reassemble the planetary gear housing. Lightly grease the shaft and all gears before reassembling. Drive the groove pin to reattach the planetary housing to the mixer, and replace the drip cup on the gear case.