I couldn't believe it. My dishwasher healed itself!
The A-1 Man was here yesterday. He and Retired Mountain Man tried every setting on the thing and it would not make the grinding noise! The final decision was that when it makes the groan again (I am saying when not if, as I am a bit pessimistic about the future of my dishwasher), call the A-1 Man back. In the meantime, I have started looking at new dishwashers trying to find one that operates quietly. No groaning or grinding.