The sprocket hole thing on Ilford Delta 400/ID-11 combination
I have used this mix successfully for over a month with no problem. Recently I got faint sprocket streaks on a roll, the second was very noticable, and the third ruined the film entirely. My method is consistent, I mix and toss 1:1 fresh stock each time, store the stock in a plastic fridge dispenser. I push 2 stops on all the rolls I have successfully developed to date...which I believe is 15 min in 1:1 at around 70. But the time/concentration/freshness/temp is invariant with the 15 or so rolls that I have developed before with no problem.
I thought agitation might be the issue. My agitation routine was vigorous 10 sec each first of 4 min, then not so vigorous every other min or so. Somewhat casual, but never a problem before. After the streaks started showing up I became religious in agitating exactly 10 sec each minute, gently, and that didn't make the difference.
I tested the camera yesterday and the 200 ISO Kodak came from the lab perfectly, so it isn't a transport or lens registration problem.
Please share your thoughts about setting up tests to eliminate possible problems. I use a thermometer on all chemicals before use, telltale stop and check the fix after each use, so again freshness and temperature are not issues.