Hello PFredrickson,
If you are getting a line/scratch in your prints, it could be caused by debris in the printer or a hardware issue. If you have already checked the interior of the printer and cleaned the inside, it would mean the printer needs service. The line that you are getting in the printout would point to a problem in the part that applies the ink to the paper.
To resolve this issue you can send the printer in to our factory service center for repair/replacement. To see which service center you would send the printer to and what service options you have, you can log in or create a Canon service account using the link provided HERE.
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