I have a Hampton Bay with a light. The light works but the fan does not. I can feel a slight hum of the motor and sometimes it appears the blades may move a bit but really there is nothing. It is about 15 yrs old. I have another one like this, same age and it works fine. Before I start taking it apart, I thought you might give me someplace to start.

This isn't answering your question, but why not just replace it? In my experience, fans are generally inexpensive and simple to replace. You will get a more efficient fan which may, ultimately pay for itself.

I thought about doing that but then if it was something that I could fix I'd do that first.

Do the blades turn freely by hand?

General ceiling fan troubleshooting and help FAQ- Ceiling Fans N More