Hi everyone! I need some advice, fairly urgently. I have a Canon F-1 New, and have been testing it without film in the camera. After working well for a few shots, the shutter doesn't seem to engage, nor can I wind the shutter on. I'm really not sure what has happened, but the camera appears to have blocked. Does anyone know of any safety systems, or any way to free up the winding mechanism? Any help would be gratefully appreciated! Kind regards.