The HP/Canon line has the toner and drum all in one. Other models differ. Many toner only models require a drum kit which folk find too pricey. So the printer is replaced rather than fitted with a drum kit. Also, you find the owner asking if the drum kit will fix it. The answer is it should but that's not good enough and the printer is recycled.
I was given a very good ex office laser printer.
It works fine EXCEPT that printed sheets have a grey smudge across each page and I'm wondering if this would be corrected by simply replacing the toner cartridge as I thought that everything to do with the printing was within the toner cartridge.
I don't want to spend a lot on a new cartridge to discover I still have the problem.

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