Pretty common problem, I haven't taken one apart, but I believe one or more of the plastic gears start slipping on a common shaft .
A few members here have taken it apart and performed the necessary repairs, but the only real problem part, is the crimped on bezel, not available to us, but if you are careful you can uncrimp it and reuse it .
Only other option is to send it to a repair shop .
One of our members that lives in the Sandyeggo area, recommended a shop there, can't remember the name, their prices were the lowest I've seen for the repair .