Why R1 and R4 ?
I swapped the R1 with R2 but no result.
Used the cleaning thinks.
It happens when I moved the printer from one location to another.
Any other suggestions?
Swap R1 and R4. Or reseat R1. Use cleaning wand under drum (orange tab on machine side) after swap/reseat.
R1-R4 are underneith your toners
My xerox wc 7530 has a problem with black texts. I replaced the cartridge, but no succes. When I print text in colors its fine. It only affects black textes. Black grafics are OK.
When I print text with RGB 0,0,1 the printed text is OK.
See included pdf