After reading about others' experiences, decided to try replacing the water inlet valve on my 20 year old Gaggenau dishwasher. This was the problem and the part from AppliancePartsPros was a fix.
On the Gaggenau dishwasher, remove the front lower bottom panel and you will see the water inlet valve at the front. My friend did the work, so I'm not sure of all the tools he used, took about
an hour, plus cycling the dishwasher through just to make sure it ran okay.