4K5SSOB0 KitchenAid Mixer - Instructions

Repair went well after I figured out how to dis-assemble the mixer. Used straight & phillips screwdrivers and a small hammer & punch to drive out 3 pins. Ordered part# PS734233 pinion & shaft as shown in the parts page, it arrived on schedule, received part # 240210-2. Only problem was the new pinion had 10 teeth, the old/failed pinion had 11 teeth. Could not learn from anyone I called at PartsSelect or Whirlpool if the 10 tooth pinion was the correct part to use.
The teeth appeared to mesh with the mating gear,
installed the new pinion, reassembled and it worked fine. Not sure if it made a noticable difference in the output shaft speed.

I replaced the phase control board because the mixer had only
one speed and was surging. I noticed from other posts that it
is important to note the setting of the speed plate before you
remove it in order to remove the phase control board. Also be
careful removing the associated 'slip-on' terminals as it would
be easy to damage the speed plate. If I ever do this again I
will go ahead and replace the speed plate, probably the cheapest
item to replace. The operation was a success and the mixer is
back in business. Thanks.

I watched a YouTube video all the way through, then watched each segment and followed along with the video. It was messier than the professional repair guy, but it worked out fine. This is not a difficult repair when you can watch a video and follow along. It saved me about $130.

Used youtube movies to disassemble the mixer and found that the gear was stripped. I kept the screws in labeled ziploc baggies so I wouldn't forget which screws went where. Once the part arrived, it was very simple to replace the gear. I regreased the mixer and then reassembled. The trickiest part was how greasy everything was! It was also hard to get the pin through the beater hub - I found a video that suggested using a very slim screwdriver to thread the hole before inserting the pin. This was the most involved part replacement I've done on my own, and it was very satisfying to get my mixer back in working order!

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

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

watched how to repair

I watched the university of YouTube videos, and followed their instructions.

Followed web site's videos. One step left out of video.

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

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!

replaced gear, and brushes.

Watch U Tube video. Take care to keep track of disassembly. Hard part was to have 4 types of screw drivers to fit the different screw heads. Be sure to clean broken gear clogs out of the grease. Parts select lady was a great help. Download Parts select diagram for extra help. Time and patience!

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!

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.