One of the HP LaserJet 4100s in my office has a problem that is hard to describe. I'll link some scans of the pages it prints below so that you can see exactly what is going on. My best guess is that it is printing vertical lines in the wrong order.
Here is a list of things I've already done to solve the problem, none of which seems to have had any effect at all:
The printer asked for a maintenance kit, so I purchased and installed the requested kit per the provided instructions. The maintenance kit included a fuser, so note that the fuser has been replaced.
I messed around in the printer settings and changed things like pitch, font, etc. None of which worked. After all of that, I reset the settings back to factory defaults.
I've replaced the toner just for the heck of it, with no improvement in print quality.
I tried printing configuration pages from the printer itself with the data cable detached, and the problem persisted. This tells me that drivers are not the issue.
Here are links to scanned versions of my printer output. There is nothing wrong with the scanned images, they represent the printed pages well: