Dark streaks with duplicated text

[Graceish]

When we print or scan, the printed page will have 1-3 dark streaks which include text from higher in the page. This happens regardless of where we print from (excel, email, images), and it happens when we print AND when we scan. We've tried cleaning, unplugging, etc. Any ideas?

[Valsimot]

If you are using non-genuine black toner it could cause that defect. Also, you might have some fuser issue.

[Graceish]

Thank you for your reply!

What is your recommendation for diagnosing if it's a fuser issue?

[Valsimot]

Use some word document with text only and change the colour of text from black to red and print several pages ( that will eliminate black toner). If the print quality is good without lines and repeated text from above then you have defective black toner.
If you had fuser issue then above text would be repeated, since you have those weird black lines fuser can't do that.

Can you print quality page from printers menu scan and post here?

[Graceish]

I printed a standard agreement we have. I printed 4 in red, 4 in yellow, and 4 in blue. All 12 pages are still showing the problem.

[Graceish]

And the requested Quality Page:

[Valsimot · Accepted solution]

I would blame it on a black toner cartridge.

[Graceish]

That did the trick. Thank you!