Output Paper Becomes Dirty (Cleaning Inside of the Main Unit)
If streaks appear on printed output, or random parts of the printed image are missing, the inside of the main unit may be dirty. In this case, perform automatic cleaning of the inside of the main unit.
1.
Press 
(Settings/Registration).
(Settings/Registration).2.
Press [Adjustment/Maintenance] → [Maintenance] → [Clean Inside Main Unit].
3.
Press [Start].
When cleaning is complete, try printing again.