HP 2600n Laserjet Ghosting. Prints multiple, faint repeats down the page. Changed all toner cartridges, still happening

SOURCE: HP LaserJet 2600n

It sounds like it, but before you replace it you might want to troubleshoot this through the HP Toolbox (the software would have come with the printer) if you haven't got it, download it from www.hp.com (it's straight forward and easy to use)

SOURCE: hp laserjet 2420 printer printing completely black pages

remanufactured / compatible toner? sounds like defects to me. try OEM, or another supplier

SOURCE: HP 2600n - pages coated with blue toner. Inside

can be one off to issues.
1. If the toners are original HP?
The waste bin can get choked with toner, usually on the left hand side, the excess waste will then be forced out past the sealing blades, forming sprinkles on both the paper, and the black transfer belt. Usually shows when toner getting towards empty.
2. If the toners are recycled this will happen if the cartidge is not stripped and all the waste toner is not removed from waste bin, the waste bin will quickly overflow onto your page, and belt as before.
B. As these cartidges rarely are empty when the Printer tells you it is, the drill and fill merchants usually add a full charge of toner through a hole they drill in the toner hopper, creating toner overload. The excess toner is pushed out during the early printing process, quickly overfills a waste bin that hasn't been emptied, creating the problem youv'e got.
Proffessional recyclers supply supply quality toners, which we suspect you need to find.
Cheers
DeJudge

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SOURCE: Faint printing

Indeed, the problem here is dust building up on the scanner mirrors. The mirrors are hidden deep inside the printer, but if you have an hour to kill, you can disassemble the printer, clean them off carefully, and solve the problem. See the very detailed PDF disassembly guide at http://forums11.itrc.hp.com/service/forums/bizsupport/questionanswer.do?admit=109447626+1221679079368+28353475&threadId=1182873 . Solved all my problems.

SOURCE: HP 2600 ghosting

It is a massive pain but a solution that worked for me is to run a 'clean' after every card stock sheet. I know it's wicked awful but it actually worked and I had to run 100 times (one for each good color card stock)
First put plain paper in tray 2
Next
Hit left arrow until you get to 'system service' and press green check
Next
then go to 'clean' and press check
Now it should print a clean image without ghosting