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, clean the inside of the main unit, as described below.
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.