Thanks for everyone's suggestions. I don't think it's the bobbin area, so we can rule that out. The springy wire just won't spring. It's stiff and drops down when the thread puts pressure on it. There is a small groove on the back of the part that has the +and - on it, which looks like it should hold the spring in place, but it doesn't. It might be too worn. Or, I'm just not putting it all back together correctly.
This is my own, personal machine that I've had since 1972. It's not something that I bought off of EBAY. This machine has a LOT of miles on it, but it's still holding up well, other than this problem. It's also my baby, so I really need to get it fixed up right.
~ Cindy