I have a Hampton Bay ceiling fan Model 52-RDT. The lights work, but the blades won't turn. When I turn it on, the motor hums very quietly, and the blades jerk very slightly, like it wants to run. What could be wrong with it?

Thanks!

Is it new? Did you just wire it, or has it been working?

No, we bought it about 8 years ago. It was working fine before.