Black line is on the edge or part of the page is covered in toner
A single, broad vertical line of toner appears on the page, or also one side of the page might be black. The line will be vertical but have a fuzzy haziness or a gradient on at least one of the edges.
The line might be in different locations on the pages, as well, depending on when it was printed.
Reseat the toner cartridge
The toner cartridge or Imaging Unit (IU) may not be seated correctly. This type of print quality issue can often be resolved by just re‑seating the supplies. When installing the supplies, make sure the left and right-hand sides of the cartridge/IU are all the way in. The cartridge/IU should click into place when correctly installed.
Bright light/sunlight entering the printer
Light can enter the printer through the vent for the fan inlet. If too much light gets inside the area pointed to by the red arrow in the image below, the printer may exhibit the print quality issues described in this document. Hence, it is recommended to position the right-hand side of the printer away from bright light, especially sunlight.
If, however, the printer cannot be moved or relocated, a cover can be added to the fan inlet vent to help block light from entering the printer.
Note: For information on how to obtain this cover piece – Part Number: 41X0053 – please contact Lexmark Technical Support. See 'Contacting Lexmark' at the end of this document for details. The subsequent section will show you how to properly install the fan cover.
How to Install Fan Cover on a Lexmark MS71x, MS81x, MX71x, & MX81x
Note: This part can be installed by the end‑user without the use of any tool. No dismantling of the printer is required when installing it.
Familiarize yourself with the cover piece. The cover can only be installed one way. The correct orientation is marked on its back with an arrow and the word "UP".
Install the bottom of the cover onto the hooks on the bottom of the vent.
Rotate the top of the cover into place and secure the cover at all four latch points. Make sure the cover is securely installed.
LEGACY ID: SO7520