XEROX 1000 Cyan Color Some time Missing problem

[UzairAli]

My Xerox 1000 is working well but after 4 to 5 hours working it gives problem in Cyan color missing(Even in Color Test Strips Cyan Missing). Some time after restart printer and diagnoses parameters it work well, some time same fault remain. Some time switched off machine for 30 minute fault solved. I change following parts to solve problem but failed.
I have done following procedure to solve problem
1. I have Change Drum
2. I have Change Charger

So please guide me.
Waiting for your kind response
Uzair

 

[DYP]

1st BTR, Developer housing, Laser would be next on your list to change. Try each one in that order first.