It is probably the developer housing, especially since you replaced everything else and tried other stocks.
Hey, I have a xerox dc 252 (400k pages) and I have a problem with a light grey background and/or darken lines on it
[it`s not periodic on page]
When I print 100 page they are more and more stronger on print, and after brake/off and another file there are lighter.
Problem is in printing and copying.
I change: itb belt, all image units, and replace fuser but it doesn`t help.
Can anyone help me with this or maybe know what happen?
I have attached a file, specially prepared contrast in photoshop to see a darken places.[serial yellow dots between on it - doesn`t matter ] / grey arrows = print direction.
Best regards
O.Z.