Several printer system factors could potentially lead to dark vertical streaks, as depicted above. Use the decision tree below to help diagnose the potential source and recommended actions to resolve the print defect.

Non-genuine Lexmark Supplies / Refilled Cartridges / ‘Compatible’ Supplies
Using of Non-Lexmark supplies can result in damage to printer components and in multiple failures, including degraded print quality within the system; i.e., the effects of using such non-Lexmark supplies are not limited to the imaging unit, printhead, fuser, transfer system, and paper feed reliability.

Slow Printing Configurations
There are some instances in which the printer will slow down its printing speeds in order to try to provide the operating conditions required to print a specified job. The printer will still operate at these slower print speeds, but in many cases, the intention is not to be printing at the slow speeds for extended periods of time. Examples of some slow printing scenarios include batch narrow media and quiet mode, which force the printer to perform slower.
For example, if you print A6 media in large batch jobs (50 pages at a time), some of the devices might experience significantly slower printing, and if done often enough, could induce an issue with print quality.
To prevent this from occurring, make sure that Quiet Mode = Off and Resolution ≠ 1200 dpi.

Heavy Usage when Printing
Depending on a variety of factors, the vertical streaks could also appear on the printout if the user has been printing continuously for more than an hour.
Should this happen, make sure to inform the user to allow the printer rest for 15 - 30 minutes without turning the printer off.

Paper Debris and Fibers
In most cases, this is not a concern, but some media can produce more debris than others. (Different media types are processed in multiple ways.) Debris from the media can be carried into the printer and electrostatically attracted to specific components. The potential level of contamination can depend on the material, any extra finishing steps like perforations, the manufacturer’s process controls and quality requirements, and storage and usage environments for the media.
Note: Loose debris found in the back of a paper tray generally indicate that the media being used has a higher propensity to deposit debris within the printer.

Continuous Printing Setup
If the user prefers heavy usage when printing, it is suggested to configure the Engine Setting 9 and set the value to 4. Changing the value will disable the algorithm that is causing the print quality defect.
Note: Changing the Engine Settings can possibly cause a different Print Quality issue, make sure to consider this as a last option.
To change settings, please refer to the steps below:
- Access the Diagnostics menu from the home screen by pressing * * 3 6 on the control panel.
- Navigate to: Printer Setup > Engine setting [x]
- Select a setting, enter a value, and then touch OK.
If the issue persists, search for more information related to this issue or contact support for further assistance.