Before I call Hasselblad service (it was CLA'd recently): there's a new problem occurring with either the 2000 body or my two well used A12 backs (one back holds self developed B&W, and the holds lab developed color). Several negatives display a 1/2" wide light-leak kind of ghost line horizontally across the middle of the negative, but not quite reaching edge to edge (horizontal, when holding the strip up and down). On either side of this ghost line, the negative is dark. Sometimes the adjacent negative is perfect. Sometimes the adjacent negative is black or deep gray. As I say, the problem has just started. I do switch backs regularly, and perhaps the back isn't snapped tight to the body, but that doesn't account for the 1/2" line being horizontal on the frame. And worn seals (on both simultaniously!) wouldn't account for the perfect negatives. Any clues, folks?