Bob really knows refrigerators and is hard working, polite, and went way beyond what I expected from a repairman. He analyzed the problem quickly, quoted me a reasonable price for the repair, went to his truck for the part, and installed it in about an hour. Then he turned on the fridge, listened about 3 seconds and said the repair was not acceptable (too noisy). He called his suppliers to find a better part, drove to Burnsville to pick it up, put the new part in, and our 23-year old Whirlpool is as good as new. He honored his original quotation even though the new part was more expensive than the first one.
If you don't care about the details, quit reading here.
The part he replaced was a small fan that is behind a panel in the freezer section (freezer is on top). The fan blows air over the evaporator coils to distribute cold air to both the freezer and the refrigerator section. The compressor, which cools the coils was working fine, but the cold air was not being distributed properly.
As for Thumbtack, I had never heard of it. I was up at 4:30 a.m. worrying about the refrigerator and went on line to look for a repair service. I found Thumbtack and answered a few incredibly easy questions and received a prompt e-mail that I would receive bids within 24 hours. By 8:30 that same morning, I had Bob's bid for coming to take a look at the fridge. He arrived before 10:30 and went to work.