Skip to Content Information Center
Lexmark MS421

Lexmark MS421

Print Quality Defect ? Random Spots or Marks on the Printout

Affected products



in title bar above for full list of affected products.

Issue description

When you print a document, the printout has random spots or marks of toner on the page. These spots or marks have no repeating pattern to them.

Random spots or marks on the printoutLeading edge of paper stack

Possible cause

This defect is most likely due to either the waste toner sump on the imaging unit being full, or to debris blocking the toner from entering the waste toner sump.


Cause of issueDescription/Issue resolution
Non-genuine Lexmark Supplies / Refilled Cartridges / ‘Compatible’ Supplies Use of Non-Lexmark supplies can result in damage to components and result in multiple print quality issues. This includes degraded print quality within the printer, including but not limited to, the imaging unit, printhead, fuser, transfer system, and paper feed reliability.
Debris Blocking the Cleaner in the Imaging Unit

From the printer's control panel, go to Menu > Help > Print Defects Guide. This will print a document that includes a distance gauge, which can be used to identify the affected component in the printer that is causing the issue.

There are many cases in which the cause of the print quality issue is found in the imaging unit; replacing this assembly should resolve the print quality issue.

Imaging Unit Waste Toner Sump is Full

The imaging unit has an estimated life for the waste toner sump. This means that the amount of toner contained in the cleaner portion of the imaging unit is measured, and if a small defect occurred in the imaging unit, it could potentially fill the imaging unit cleaner sump, thus leading to random spot or marks on the printout.

Replacement of the imaging unit should resolve the issue.


IMPORTANT!The part numbers listed are correct as of April 2018. Please check? the updated part numbers at the Lexmark part store before ordering.

Printer ModelPart numberDescriptionRemoval Procedure
Lexmark MS/MX 31x/ 41x/ 51x/ 61x 50F0Z00 Imaging Unit Please check User Guide for the Supplies removal procedure.
Lexmark MS/MX 32x/ 42x/ 52x/ 62x 50F0Z00 Imaging Unit

Lexmark MS/MX71x/81x

52D0Z00 Imaging Unit

Still need help?

If you need additional assistance, please close this browser tab or go to the Lexmark support site, type your printer model and locate

Get in Touch with Lexmark! for contact information.
When calling for support, you will need the following:

  • Affected printer model/'s

  • Printer serial number (If you need help locating these, xref_HO3865_xref.)
  • Toner/imaging unit/waste toner bottle part number and serial number

Please be near the product/s described in this article to expedite the support process and reduce callbacks.


Was this article helpful?