"The dishes on the top rack are filthy, bottom rack cleans great."に関する回答check to make sure your fill valve isn’t malfunctioning. if the water level in the bottom of the tub is low, then all the cleaning of crud won’t make the pump send water to the upper rack and in particular the top of the washer sprayer. it’s fairly easy to diagnose a faulty fill valve. run the washer and open the door when you hear it attempting to forcibly wash the dishes. if the overflow switch hasn’t tripped off the feed of water through the fill valve, then you have a malfunctioning fill valve. the switch trips when the bottom of the washer tub is quite full. it’s a cheap and easy fix. i’m not saying it’s not crud the crud in the pipes, i’m just saying that sometimes it’s simply a lack of water.