HP Laser Jet III now has three broken horizontal lines across each printed page after replacing the toner cartridge and cleaning the fuser Roller and Fuser Assembly Cover and corona wire. Why did this happen all of a sudden? Do I need a new drum? Do I need a new Fuser?
I can see a couple of possibilities here. One: The cleaning blade for the drum could be damaged and not all of the toner is being cleaned off of the drum between pages. Two: The drum could be damaged and the damaged parts of the drum are not accepting the changes generated by the laser. I don't think you have a fuser problem because if it were that, the toner would probably smear when you touch it. Typically, I would say it is the toner cartridge but you replaced it and still got the same problem. I would inspect the drum cleaning blade first. That would be the most cost effective first option. Hope this helps. Good luck.
Sounds like a bad (defective) toner cartridge. You can also try cleaning the corona wire again.
Usually answered in minutes!