Hi, I have a Polaroid Press shutter with 75mm Tominom mounted in the Polaroid close up attachment with the ring flash. I am trying to remove the lens and shutter to use just the shutter but am having problems. I have got the inner mount out of the box with the ring flash to reveal the locking rings, one for the shutter the other for the rear cell ? but both seem to be locked solid. Has anyone removed similar ? have I missed something obvious like grub screw, can't see any, or right hand threads ? Thank you in advance.