1. Please upload a picture of the defect.
2. "Vertical" or "horizonal" defect is only helpful if we know which direction the paper is loaded in the paper tray.
3. Have you tried cleaning all 4 laser windows with the wand? Do you still have the cleaning wand?
Hello, Vertical lines in prints are an early warning sign of a low ink cartridge, which may show up before the printer's low ink alerts start. You can fix the problem by replacing the low cartridge. Gently shaking the drained cartridge a bit may help to get another few prints out of it without vertical lines.