LeFever cocking indicators are a simple, flat spring powered button that is forced out of the sideplate by the cocking of the hammer. The sideplates on LeFever's are held in place by a through screw and a small lip on the front edge. I'd look before I spent money particularly since most current gunsmiths have never seen a real LeFever. The cause could simply be the flat spring has worked out of the cut in the button. Best, Dr. BILL