43XC-01S
Black Streaks that are Perpendicular to the Direction of Feed Appear in the Printout and the Color of the Streaks Gradually Fades
Printouts may be distorted because the toner is fixing to paper that is too dry. Check the solutions below.
← Feeding Direction
* 174 mm (6 7/8") cycle
Remedy
Avoid storing paper stock in extremely low humidity environments for a long period of time, unless it is suitably wrapped.
Unwrap the paper immediately before you load it into the machine. Keep unused paper in a closed package and use it as soon as possible.
To improve this situation, adjust the value for <Adjust Fixing Speed> to match the specific characteristics of the paper.
Press 
→ [Preferences] → [Paper Settings] → [Paper Type Management Settings] → select the type of paper you are using that is having this problem → press [Details/Edit] → [Change] for <Adjust Fixing Speed> → adjust the fixing speed toward the plus end.
→ [Preferences] → [Paper Settings] → [Paper Type Management Settings] → select the type of paper you are using that is having this problem → press [Details/Edit] → [Change] for <Adjust Fixing Speed> → adjust the fixing speed toward the plus end.
"Paper Type Management" > "Adjusting the Fixing Speed" in the User's Guide