Pro1106 Copy Qaulity

[Voltage]

Hi Guys

If have a Pro1106 that keeps on messing toner just beneath the dev. rollers. The drum holder also gets full of toner. The copies will then because of this have messy edges. Especially in the corners. I have replaced the developer, carona wires, cleaning blade and opc. Even swapped the dev unit with other use unit. The machine has about 6500k copies on. VSG is 3.93 and VSP 0.37. TD density is 2.53

Any ideas???

[Coptech]

Clean all filters including the one by the op panel upright. Also check the hoses to the toner pump and to the toner hopper to make sure they are not plugged.