Although it's almost impossible to see on the scan, the extra density (I don't know what to call it!) goes across the frame and out right to the edges of the film (past the frame boundaries) and fades to the top of the frame. The more of these I look at, the less I think it's a loading problem (how 's that for an about turn!) as the films where that has definitely occurred are jet black (longitudinal edge marks). I have a couple of tests in mind that might isolate the problem to the camera or my handling of the film, but that will use film for no reason, so I thought I'd ask for opinions 1st! So... thoughts?