I have a bit of a problem with my old Nikkormat EL - model film camera... It won't trigger. I've read that a built-in locking device prevents the shutter from being released unless it is fully cocked and the film has been advanced a full frame. I maybe think that the final picture didn't advance a full frame, which now keeps the camera from neither triggering nor being able to turn the lever more than to the "ON" position, like this.. Even though the film is now rewinded and removed. Does anyone know what to do?