Wonderful writeup. Thanks!
I'll share my story
I moved into a house 2 years ago that has a DW80J7550US/AA (I believe this was the initial version). s/w version 7136 (which is odd, since 7134 is supposed to be initial). The dw never washed well, and one day I noticed a magnet in the bottom. I put my phone in a waterproof pouch and recorded what was going on inside. Found the waterwall never moved. Found all the posts about magnets, and realized the magnet I found was supposed to be attached to the vane.
I positioned it there, and the water wall started working. It would move when starting the dw, but made a loud grinding sound when the waterwall cycle was running. I observed the waterwall cycle would run for one minute out of a 60 minute express wash cycle, which was not good. I tried blocking the waterwall motion with my hand and realized it was really easy to prevent it from moving. So, the waterwall will move when there is no spray hitting it (which happens at the start of the cycle, when the dw is testing it), but when spray is hitting it, it gets stuck, and the dw realizes it is not functional.
So that's why I got only one minute of waterwall use out of the 60 minute wash cycle. I got a used motor on ebay, and tested it when it arrived. It too was easy to stop the motor when running (just held the shaft with my fingers while it was running -- I connected AC to the white plug connections). So, it was not going to be any better than the motor in my dw.
I followed Matt Rampone's instructions in his great video:
But just used gorilla super glue (cyanoacrylate) to glue the white plastic disk to the white plastic drum inside the motor (instead of epoxy). Worked great! The motor could no longer be stopped with my fingers holding the shaft when running. I put the new motor in my dw and life is now grand. I now get 3 minutes of waterwall, alternating with 3 minutes of top wash.
(I could probably have made the same repair to my original motor, rather than getting a new used one, but having an extra made things easier).
Thank you so much for your post! I had just about given up on my dishwasher, when I stumbled upon this.
And now it is running again. At least for the time being.