White Gapping consists of light or white patches that repeat down the left or right edge of the page.
Repeating defects of a single color (Cyan, Magenta, Yellow, or Black) are usually due to defective photoconductor units or toner cartridges, and not TBMs, fusers, or other printer hardware.
Toner cartridges or photoconductor units that have not been properly installed can cause defects similar to the one pictured above. Remove and reinstall the toner cartridges and photoconductor units, making sure that they are fully seated. (
NOTE: When removing and reinstalling the photoconductor units, do not touch the shiny blue drums.)
Perform the "Color Adjust" procedure in the "Quality" menu.
Print the "Print Defects Guide" in the "Help" menu and review the print samples.
If the defect repeats down the page, use the defect ruler to determine which component is defective.
The example shown above is at PC Drum frequency, and is caused by a defective photoncoductor unit.
A swap test of the photoconductor can be performed to confirm a suspect PC unit.
For optimum print quality and reliability, Lexmark recommends always replacing photoconductor units in complete sets.
When replacing photoconductor units, be sure to reset the photoconductor life counter for each photoconductor unit replaced.