Mark F San Carlos , CA February 02, 2020 Appliance: LG Dishwasher LDS4821ST Top spray arm not spinning in lg dishwasher I replaced the upper nozzle guide, nozzle shaft and upper spray arm. I also replaced the pump gasket for good measure. Top rack dishes had not been cleaning properly. I first removed the filter assembly to inspect the main pump from above. It was clogged but after cleaning and reassembly I observed that while middle and bottom spray arms were changing position, the upper spray arm was not. I confirmed that water was flowing through the upper spray arm by placing some empty yogurt pots on a baking tray on the top rack. The ones underneath the spray arm filled up. I tried cleaning the spray arm by removing it and flushing it with water but that didn't help. When spinning the upper arm by hand it tended to stop after a few turns so I wondered if the shaft had worn down and was creating too much friction for the nozzle to turn. So I ordered replacement upper nozzle guide, shaft and spray arm and tried them out. On the same order, I took the opportunity to replace the filter assembly (still a little clogged), the pump gasket (showing signs of wear) and some broken dish rack rollers. After replacing all those parts, the upper spray arm was back to working order. Read More... 5 People found this story helpful Do-It-Yourself Rating: Repair Time Estimate: 2+ hours Tools: Screwdrivers