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Lexmark MS421

Lexmark MS421

Fixing light or faint vertical streaks appearing on the print

Issue description

The printed image appears light due to multiple small, fine-line streaks running through the text or graphic areas.

The severity and number of the streaks can differ, causing some of the light streaks to appear wider than others.

There are multiple potential causes of vertical light streaks.


Note:  Before proceeding with the issue specific steps, perform these initial steps.

  1. Make sure that the paper loaded in the tray is supported.

  2. Print the Menu Settings Page (MSP).

  3. Check the supply levels for each toner cartridge and the imaging kit. Replace the supplies that are low.

  4. Print a test page and check if the issue persists.

  5. If the print quality issue still appears, continue with the following steps.

Defective Imaging unit

To resolve the print quality defect, a new Imaging Unit must be installed. Turn off or disable Advance Start and Smart Run Out. If the same issue persists, proceed with the following steps:

In addition, user must review the following sections to ensure they have optimized their device for best performance.

Non-genuine Lexmark Supplies / Refilled Cartridges / ‘Compatible’ Supplies

Use of Non-Lexmark supplies can result in damage to printer components and degraded print quality. Non-Lexmark supplies are not covered under Lexmark warranty.

  1. Verify if the toner cartridge is genuine by using Check to Protect.

    • If the customer has provided print samples which contain vertical narrow or fine lines, check the serial number of the cartridge.
    • If there is a green sticker with a date near the serial number on the cartridge as shown, there is no need to check the serial number.
    • If there is no green sticker, check if the cartridge serial number is in one of the following manufacturing date code ranges.
      • CAA 22 147 0051 - CAA 22 234 12BD
      • CAB 22 131 06B5 - CAB 22 242 3C14
      • CAD 22 193 7618 - CAD 22 268 3F70
      • CAP 22 207 1221 - CAP 22 266 27B0
    • If the cartridge serial number is in one of the ranges above, the cartridge AND Imaging Unit should be replaced.
    • If the cartridge serial number is NOT in one of the ranges above, proceed to the next step.
  2. Replace imaging unit.

Slow printing configurations

  1. Device Settings

    • Turning on Quiet Mode slows down the printer.
      • Changing the Quiet Mode = Off improves the print quality.
      • On the Control Panel, navigate to Settings > General Settings > Quiet Mode = Off
    • Increasing Print Resolution slows down the printer.
      • Changing the Print Resolution = 600 dpi improves the print quality.
      • On the Control Panel, navigate to Settings > Print Settings > Quality Menu > Print Resolution = 600 dpi
  2. Printing Narrow Media

    • When printing large print jobs and the media is narrow can cause the printer to slow down (A6 media for example). When possible, print with a Long Edge First to prevent device from slowing down.

System Delays while Printing

There are instances where the printer is ready before the job information is received. This can cause the printer motors to be turning for an extended period before printing begins which causes extra wear and tear on supplies.

Update the printer firmware to the latest level.

Dirty Printhead

To fix the issue, clean the printhead lens. If there is no improvement to the print quality after cleaning the printhead lens, contact Lexmark support for further diagnosis.


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