Vertical repetitive defects
The print cartridge might be damaged. If a
repetitive mark occurs at the same spot on
the page, install a new HP print cartridge.
Changing the print cartridge
The internal parts might have toner on them.
Cleaning the printer
information. If the defects occur on the back
of the page, the problem will probably
correct itself after a few more printed pages.
In your printer driver, make sure the
appropriate media type is selected.
Improving print quality