I have been dealing with this problem for a while now. I have been on many sites with many suggestions that all work and then they don’t. There doesn’t seem to be one single answer that fixes it all, that is unless you contact Whirlpool and their only solution is to have a repairman come out and look at it. They give no useful advice. What gets me is that when I bought the dishwasher, I kept getting emails for an extended 3 yr. warranty for $320, which now I am glad I didn’t get because it is now 4 years later.
So, my only possible solution is to take that $320 and use it towards buying a new dishwasher which won’t be a Whirlpool.