Hello! One of my roll film backs for the Horseman is jammed. I would like some tips if you have experienced this as well... So it's a Horseman 22401 Roll Film Holder type 1 (8EXP 6x9 for 120 film), late black version, in very good shape, almost new. There wasn't any film inside and I was using the advance lever and unlock lever, listening and looking (my way of learning new equipment) when suddenly it didn't advance anymore, nor did the unlock lever change that jam... Current situation; The film counter shows "S" The unlock lever can be moved to the left, then jumps back to the right (starting position) The advance lever can be moved easily to the "out one click" position but advancing further is not possible; it won't budge! I've tried both with the interior cassette on its own, as well as placed inside the film back case (so that the hinged door is closed and presses the little lever for the counter to start) but no movement in the advance lever! Now I'm in a bit of a jam. Any thoughts?