It's not the manual rewind knob is it?
On the bottom of the camera there should be a threaded knob that looks like a battery cover only it has black rubber around it. It's missing from a lot of used 645's. And I don't meen the internal small battery cover. If this knob is there you'll know it. it unscrews. It's used to rewind the film from mid-roll in case of a jam or something. >, the other one is infront of the socket, and to teh top >(inline with the corner), and is actually a little screw socket covered by >a plastic disc.. Its not the PC cord hole, as that lives by the back of >the camera.
