I was recently given a Hasselblad 1000F and have begun playing around with it. I rounded up a manual (reprint) and it seems there is supposed to be some sort of dark slide inserted from the left before the magazine can be removed??? Trying to move the magazine latch to the right does not release the mag. If I have this right, the dark slide is missing. I would like to remove the magazine, is there anything I can substitute for the dark slide? What does it engage inside the camera to release the magazine? There seems to be a thin plastic lip running up and down, not sure if the dark slide was to be inserted on the lens side of this, or the magazine side. The film holder slides out of the magazine fine, just the magazine itself is the problem.