HP 8500 doesn't print colours only black

[psc108]

I have a HP clj 8500 which prints from the black developer perfectly but nothing from the colour ones. I have checked that the carousel stops in the right place, that the gears are enmeshed and that the drive motor turns the gears. The print process performs normally but no colour is printed. Any ideas?

 

[Michael52x]

Ya know.....
You really have to give up all the info thats needed here.
HP toners? Generics? Quality paper? Consumable status?
Usage page? Production printing or general office use?
Last maintenence? Clean,clean,clean!

 

[creativeimages]

I have an HP 8550 DN Color Laser Jet Printer with the three bay paper feeder with two problems.

One, the duplexer jams with great regularity. I have purchased two duplexers; and they do not fit.

Secondly, the print quality is bad; the printing processe leaves a lot of toner on each page. In other HP printers, there is a felt covered stick that wipes the drum to remove excess toner; but I can not find one in this printer. I do not know what I should change next; any ideas.

Thanks.