Middle arm of dishwasher not spinning

I'm the one that reported the same problem in November as "Guest". I fixed mine finally. I removed the middle arm again and noticed that the holes that spray a jet ot water causing the arm to turn aren't the ones on top. On the bottom of the arm there's a small hole at each end. I looked and one of the holes had a small piece of crud in it. I had to use the tip of an ice pick to dislodge it back into the arm. I then ran water into the arm several times hoping to get the item completely removed. I never did see anything come out but I then ran water through the arm holding it so the water could run out one end. The piece didn't show up in the hole again so I tried washing it to the other end. It still didn't show up so I guess it must have washed out the first time. It's been 3 or 4 weeks now and the arm is still functioning perfectly. Hard to believe that one little piece of trash can cause so much irritation. Good luck on this being the problem for others.

There could be a buildup of minerals that is affecting the arm, or a particle of sand or other debris.
start by looking for a whitish buildup on other parts of the interior. if so, you can get some phosphoric acid based cleaner, like shower power or clr, or shower mist from smart and final. (the latter is cheaper)
run a small amount of that with the washer empty. try a few runs. it may be really built up.
alternately, if all looks clean and the are swings with great ease, then the pump is not working correctly and there is not enough pressure. check for debris in the drain area at the bottom.
pumps usually run or they don't, so i would suspect a clog somewhere before i would think the pump is going or has gone bad.
recap. look for calcium deposits and inspect for clogs. clear calcium with chems listed above.
caution caution caution: phosphoric acid based cleaners will remove deposits in the shower on glass, tile etc. make sure the list of precautions does not include anything that is on the inside of your dishwasher.
and do not get it onto your bare hands. especially if you have a cut. its not particularly dangerous or they would not sell it, but if it gets into a cut, like around a fingernail, it can cause serious problems in some instances. aside from that, its the best cleaner you will likely find for the problem.
if you do have build up, you might have excessively hard water depending on how old the unit is. if you put in a softener and its salt based, do not drink that water. get a water filter for drinking and cooking water.
good luck
mark

I had a piece of plate in mine as well! in a couple of loads we'll know for sure!

Don in FLA -- I think you've hit the nail on the head. I (once again) removed the middle arm and looked at the underside of it and indeed found "crud" plugging the small holes that point downwards. Turned out to be tiny bits of a broken plate. Once I maneuvered them out, the arm seems to be rotating much better, and with greater upward force of spray. Thank you!

I have a GE profile dishwasher PDW828 and was experiencing that the upper tray cup holder was not cleaning properly. The dishwasher has three wash impellers and noticed that the middle impeller under the upper tray was not moving during the wash/rinse cycles. After removing the impeller blade, I found three small pieces of plastic and a fish bone in the impeller blade. After I flushed out the impeller repeatedly with water and then reinstalled, the dishwasher is back to normal operation.
It appears any debris which gets trapped in the impeller blade will prevent it from spinning properly or even at all.

Thank you! My dishes, especially those on the top, were not getting cleaned. It ended up being a little piece of paper off the bottom of a new cup that was clogging the holes. Easy fix!

Had the same issue with the middle arm: not spinning. I followed the suggestions here (and after watching a GE video on how to remove the top basket) and found some unidentifiable crud blocking the jets that spin the arm, also found a bit of stiff clear plastic clogging the main inlet to the spray arm. Thanks everyone for the tip!