When I attempt to close my manual sunroof, the crank handle will spin emitting a ratcheting sound, but no closing action results. This occurs at the end of the close cycle, when the more force is required. I know I'm stripping and wearing down something cheap and plastic, but hard to get to when it totally fails. I've attempted obvious repairs, like tightening the screw on the crank handle, but, not surprisingly, that did not help. Any thoughts?