I greatly appreciate the assistance and I see a good deal of food for thought. I wouldn't be surprised if the dropout aren't perfectly parallel and I will be checking them. The notion that something may be rubbing against something else also makes sense. When I have the bike upside down and spin the rear wheel, I notice a slight but definite wobble where the freewheel is, so there could be rubbing. I don't know what it indicates. The bike has no quick release. I don't think its not particularly valuable. Its kind of retro (reminds me of when I was growing up and 10-speeds were popular), rides well, it came almost free and I suspect its reparable without much cost.