I am hoping that someone can help me with a darkroom printing problem I am having. I am using a Besseler 67c and a 75 mm Nikkor lens and am experiencing significant light drop-off towards the corners of the print. I am printing 6x7 negatives and have the 6x7 head in place. I have stopped the lens all the way down, but the problem persists. The negatives are correctly exposed all the way to the edges. Could this be the product of a failing bulb? I have previously been able to make prints from these negs without difficulty. Any ideas as to the cause or a possible resolution would be welcome.