Report "I had a service tech at my house to repair my refrigerator. He also took a look at my Maytag WU504 dishwaser, which was not cleaning the dishes anymore. He was less familiar with dishwasher diagnosis, but found that the lower spray arm was pumping out water through the jets properly in the cycles, but that the spray arm was not rotating. He seemed stumped and called his supervisor, who suggested it might be the wash impeller. I have looked at the parts diagram on partselectdotcom and taken the bottom assembly apart to look for problems. I believe the problem is a broken spray arm support nut (part# 4). I can see where the top portion of this nut (which limits its travel) has broken off and I recall finding just such a piece in the bottom of my dishwasher just before the problems started. It appears that this nut, when properly tightened, allows the wash arm support to spin and stay in place. With the nut broken, it spins and then tightens on the bolt (part# 29) in the top of the sub-assembly (part# 9). Before ordering the nut, I wanted to confirm this diagnosis. Thanks!"