iPhone shot of the underside of the Nikon FM2n. The lever (A) needs to be bent at a right angle to lock the bar (B) in place after film is advanced and the shutter is cocked. With time, the level end bends further and further from the right angle and the bar is able to slip past, allowing the film advance to be wound repeatedly without exposing the frames. Removing the lever and restoring the right angle is a simple process, and restores proper function to the film advance lever. (Daniel J. Schneider)