This may have come up before, but the search found nothing.
Km 6330 giving a very dark shaded background. The Drum potential sensor has been changed, along with the modified holder. The main charger-changed, Dev-changed, main PCB, power PCB and inverter PCB-all have been changed.
We thought we had it licked by resetting Sim 103, which is only available in 30363036 and adjusting the setting in that sim to #120. But after two days the copies returned to the same state. I'm now bald and desperate, but hopefull :-)

How about the drum heater contacts are they clean? take the drum apart and chech the drum grounds.

Sim 100 use the * or # TO GET it to 125
try it

Thank for the replies, I'll get back to you if they help.

Check this post: background

It's not generic toner.
I've also checked the drum heater connections and that all looks good.
The strange thing is, since we brought the machine to the W/Shop, it seems to now give good copies for the first couple of hundred, before it reverts back to the strong background...wierd.

HAVE YOU TRIED CHANGING THE TRANSFER BELT?

Have you cleaned all bushings, bearings and rollers in the transfer assy?

Yep, I've already changed the Tranfer belt and I cleaned all the bushings, bearings and connections....

What about the developing rollers. Are they shinny or with a toner film on them; specially the upper one? Mark B asked you about drum grounds (inside and in the back)...

Just to throw out an idea. What about the Laser?

Have you replaced the developer? This was an issue with background in the past.

Thanks fot the replies...I have checked the drum's connections and we have changed the dev, but niether had any effect. I have just borrowed a Laser and when I get a free minute!!!! I'll try it and let you know.

We went through all this, new style cleaning
sections too. Finally corrected problem on 6330
running 12 to 15k per day by replacing drum
ground tab on shaft at rear of copier with two,
that's two, old-style RC2030 drum bushings
soldered to a wire screwed to the frame. Don't
use conductive grease, it will squeak next day.
These 'prelubed' brass bushings don't need
grease. 2030 bushings have a tab easy to solder
to. Problem is drum ground. Good luck.

Hi!
I don't know if the problem is fixed yet but check and see if the transfer belt gets coated with toner while the machine is running. We've replaced everything mentioned before. Developing unit took care of it.
Good luck!