Why is my printed page gray with barely readable text?

The fuser is worn out or you’re using an old toner cartridge. Since you’ve already tried 2 carts, it is probably a bad fuser.

Sadly, this part was made obsolete many years ago so you need to buy a rebuilt one and it may be as much as a whole new printer :-(. Unless it’s one of the few low page count ones left as many of these get run to the ground by owners, this may not be worth pursuing further. Since these are so old, find out how many pages it has logged and make the call yourself (this is more easily said than done without the EIO Ethernet card; it's a pain otherwise unless you can pull it off with a vintage Mac with OS8 or OS9 or Windows PC). If it’s high mileage (200k+), expect to need to change out a *lot* more than just the fuser; you need to do a rebuild (new transfer roller, pickup/separation pads and rollers, fuser). The problem is the rebuild cost may total it out. Watch this video to see how to do the fuser swap.

If the printer is totaled out due to the page count or parts cost, find an LJ 4250/4300 (11x17 compatible 4000 series with USB). It’s much newer and it carries the million-page endurance the 4000 series is famous for (and was the end of that era), but you need to replace the plastic swing plate gear (or assembly) as it has a tendency to wear out earlier than the rest of the printer. If you don’t want to do that job, Printer Techs sells them with the replacement gear installed but the "repaired" printers are pricey compared to others who ignore the problem. That said, these pre-2007 machines are so much better than the more modern ones because they don’t have as many electronic failures as the new ones. These old printers are the last of their kind.

I still run an HP M401n from 2012 (2007-present RoHS, but it's a proper steel frame machine that weighs 50 lbs) :-). Anything with the white chassis is a no go due to the dynamic security garbage firmware now, or that and HP+ ink DRM.