I just put a Hasselblad kit together, and I seem to have a defective back. I did not try to put a film in it yet, but I understand that even without film, turning the crank clockwise should ultimately change the frame counter to 1 and stop. This doesn't happen and the crank turns indefinitely and the counter never goes past 0. Is this a known problem? I know people will tell me to take it to a tech, but I'd prefer fixing it myself if this isn't extremely difficult and someone knows what the problem might be. Thanks!