How do I correct black smudges when printing?

replace the black image unit

Btw, I’m available to help over the phone in case u need at https://www.6ya.com/expert/normanj_7893313f0751935f

if you print correctly, the damage was photocopied unit, should be dirty, it should be cleaned.

change the black ink cartridge

check the fusing unit in the rear of the printer and check your print cartridge for smudges.

make sure ur catridge is not leaking just remove the catridge and clean with tissue paper and try.

I also had this issue, waste tone was comming from the transfer belt, had a good clean out been good for months now.

Bad black cartridge.
When making photos this printer mixes all 3 colors to make a black.
Is this what you are referring to ?

Try reducing the print resolution using the menu buttons. Does it smudge with coloured prints? If so then the fuser unit is faulty. If it is only black that smudges it is likely to be the K Developer unit. Ensure that you are using genuine toners, not refills or third party as the quality of toner can cause similar results.

try replacing the toner cartridge if that does not help it may need a fuser replaced

- Try to reallign the cartridge, run a print test, after that if the issue still persist - uninstall and reinstall software - run test and re-allign again the cardtridge using software. run print test again.