Hello VaRob,
Sounds like you have tried everything already, so it would be a hardware escalation: 1-800-835-6100.
I have a phaser 4600 with a page count of 85000. After replacing the fuser, drum cartridge and toner, pages are coming out dirty and there are drops of toner across page every 4 inches. I have also cleaned as much of the unit as possible. Any help would be appreciated.