A common problem for Springair type retracts is a twisted retract frame caused by non-parrallel mounting rails. Remove the retract from the wing and check it's operation. If the retract now works properly, set the retract back in the wing and note where a gap exists between the retract frame and the mounting surface of the rail. A washer or two between the frame and the rail will act like a shim and allow you to reinstall the retract without the frame twisting which will cause a bind.

John