The washer sounds normal during the fill and drain cycles. When it starts the wash cycle, it emits a buzzing sound, just recently. I thought this would almost certainly be the circulation pump/motor, and I replaced both (they came as a unit). This did not fix the problem.

Before I did that, I checked the sump for debris and cleaned it out. When replacing the circulation pump I tried my best to confirm the tubes were clear (just using my finger, nothing fancy).

The sound is loudest underneath the dishwasher, naturally. I checked for loose items that might creating a vibration/buzzing sound but didn't find anything.

Even though the sound seems to be loudest underneath, I removed what I could from the inside. I took the rotating rinse arms out, took everything out of the sump that I could, etc., just to eliminate everything I could. Still the buzzing continues.

I'm running out of ideas. Thanks for any help.