Isolated the problem by removing the bottom panel and running a rinse and hold cycle. By holding the drain pump housing during the drain cycle I could feel it running and also hear the grinding noise. I then ordered a new pump, which was on my door step within 48 hours. Replacement was easy with the help of a YouTube video I found. I ran a test with the rinse and hold cycle no more grinding noise. I've run the dishwasher six times since and problem is gone.