There is a little 'release' button in the middle of the spool release( take-up side) that allows the 35mm film to be rewound.

By John Suckling on Tuesday, June 17, 2003 - 11:28 am:

I have just bought a s/h Mamiya 7 II togther with a panoramic adapter kit. The kit didn't have any instructions with it unfortunately.

I've worked out myself how it all fits together, but the problem I have is how do you rewind the exposed film back into the 135 cannister when using the kit?

The rewind handle on the outside won't turn as the take-up spool only goes in one direction ie. forwards, not back. Is there a way of releasing the take up spool - the only way I have found to do this is to open up the back, but then you need a darkroom or changing bag.