Well, it took a while to diagnose. We went to the co-op and the first mechanic thought maybe the rear hub was a bit loose. I could feel a very tiny bit of play. I tightened the hub. The problem remained. The second mechanic, who was the one who helped me yesterday, looked at and felt the wheel and said that the spokes were much looser than yesterday. His conclusion was that the spokes needed new nipples. He also felt that my husband should have a 36H wheel and double wall rims. Of course, they didn't have any 8/9 speed wheels so we are off to shop. They must have had 100 seven speed wheels. To bad I didn't build it up as a seven speed.

At my leisure I'll go back and rebuild the old wheel and use it as a spare for me and as a learning experience.