I want to tell this crazy answer. My whirlpool would fill and drain, but not wash. I was getting ready to replace the pump and motor assembly. There isn't much room to work under the machine so I thought I would try one last thing. I removed the lower dish rack, lower spray arm and filters, then I wacked the sump assembly a couple of times. I reassembled the machine, started a cycle and guess what, it started to work just fine.