Swap the Magenta and Cyan drum, if the issue follows the drum, the drum is the problem, if the issue stays with magenta, the developer is the issue
It is possible to be from drum cartridges. Try to replace them.
I have a XEROX Versalink C500 Color laser printer. A few weeks ago it started printing FULL background color when printing simple black text (and anything else). Cannot find a solution to solve the problem - have searched a LOT. Have ALWAYS used only genuine XEROX product (toner, etc.). What can I do to fix this. Right now it is worthless to us and I am afraid I am going to have to replace it. It is 12 months old.