We have a 7435 we purchased used as a backup to our main copy station. Recently developed a white line (void of Toner) on the magenta only, line is about 3/16th in wide. Swapped in a new drum with no effect, cleaned print heads, no effect, ibt belt is fine. So we swapped in a brand new developer housing (you could see a void on the mag roller with a flashlight). Once it was primed up with toner it developed a line in the exact same location. With a flashlight shining in through the drum opening you can clearly see a void on the mag roller just like the initial developer housing it replaced. I'm stumped, what should I look at next, and what could cause two different developer housings to develop a void (very quickly) in the same location on both mag rollers.
Thanks