Oki LP-1040 Maintenance Manual page 258

(12) Black belts (vertical)
Black belts not present in the original image are printed vertically.
Print sample
■Cause and solution
(a) Cause:
Light-induced fatigue of the photoconductor drum
Solution:
Block the light if the Printer is reached directly by sunlight.
(b) Cause:
Charge wire, cleaner blade, or photoconductor drum malfunction
Solution:
Replace the process cartridge.
Chapter 7 Printer Image Quality Problems Troubleshooting
Possible problem locations
- Process cartridge
- Fuser unit
- LED head
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