I researched the problem and found that the gear case was most likely the problem. Purchased the gear case from Appliance Parts Pros. Exact OEM part. Most of the disassembly went smooth. HOWEVER, removing the old gear case was a challenge. I finally had to use a small bottle jack and a wood brace to press out the old gear case. WHEW. After a thorough cleaning, the assembly went smooth. Now the rinse is as new - much quieter. The included "recalibration" instructions did not work. Found similar instructions on the internet which did work. Now washing like new.
This part from Appliance Parts Pros was correct and competively priced.