Hi again. I have just looked at The Bronica Manual by W. Cheung. It doesn't cover the SQ winder, but has troubleshooting for the ETRSi version. It says that you must align two red dots on the winding linkage when attaching the drive. " For correct positioning, revolve the linkage past the point where the two dots coincide and then turn the linkage back clockwise until it stops. " if you don't do this, it seems to say that the shutter will fire, but winding stops midway. This info is under a section headed 'Practical hints for Motor-drive E use. I hope this helps. Alex