43XC-01L
Streaks that are perpendicular to the direction of feed appear in the printout
The intermediate transfer belt is warped. Clean inside the main unit several times.
← Feeding Direction
Remedy
If you have not used your machine for a long period of time, the intermediate transfer belt may become warped. If this happens, clean inside the main unit several times.
Press 
→ [Adjustment/Maintenance] → [Maintenance] → [Clean Inside Main Unit].
→ [Adjustment/Maintenance] → [Maintenance] → [Clean Inside Main Unit].
"Maintenance" > "Routine Cleaning" > "Output Paper Becomes Dirty (Cleaning Inside of the Main Unit)" in the User's Guide