Recommended that you have a tech come out and look at it might have a bad LED assy. for the Magenta Image unit. All other color print OK? Can you print gradation test pattern for each color in service mode? Meter count, details, stop 00 stop 01 Test Output Gradation pattern select magenta. If you open the side cover after printing a document with the color magenta try to catch a print of paper do you see the color magenta on the transfer belt if yes the drum is ok could be the transfer belt magenta 1st transfer roller on the belt replace the belt assy.
Btw, I’m available to help over the phone in case u need at https://www.6ya.com/expert/normanj_7893313f0751935f