Hi,
It maybe possible that you have a damage Image Unit. You already did what is necessary to check for any dirty. Any way recheck:
If this doesn't help you should consider place a call.
Regards
Rui
Our phaser 6360 recently started to produce a white streak on all printouts if cyan toner is used. We did a test print and conformed it. We removed the imaging unit and did not see any particles on the rollers. What could be causing this? It said we have around 20k-30k more pages left for the imaging unit.