LaserJet 2420 grey background
Here's part of a page printed: LJscan1014.jpg

Most of the left side of the page has a greyish irregular background, maybe 10% grey. The text is a bit faded and sometimes broken up.

I got this printer a few months ago, Has 207,000 pages on the clock.

I had another printer, same model, that was having a lot of jamming issues, so I took its 90% full toner cart for this and it printed perfectly.
The fold out "tray 1" was damaged though, so I took the tray from the other printer. To do that I had to take off several panels and take the toner cart out. I did try to protect it. Cleaned dust out of the printer while I was at it. The print seemed to be still OK, then. I disposed of the old printer (no room for it.) But shortly after this grey vertical bands appeared. I made a couple of the cleaning pages and ran the clean cycle, but made no obvious improvement.

Is this some damage I did to the toner cart when doing the repair & clean? Can it be fixed, or will a new cart fix this?