NEC Super Script 4400 Maintenance Manual page 241

19. Mottle - Variation of the optical density is found in the image.
Main Causes
1. Transfer unit is not locked into place.
2. Improper assembly of the transfer roller.
3. THV output of DC high voltage unit is not normal.
4. Failure of the toner module.
5. Deformation of the paper.
Fusing Unit
Transfer Unit
Paper Discharger
Unit
Transfer Roller
Transfer Drum
Paper Feeding
Roller
Countermeasures
1. Confirm that the transfer unit is firmly locked into place.
1. Ensure that the transfer roller is properly installed.
1. Replace the DC high voltage unit with a new unit. (See Chapter 7)
1. Replace the toner module with a new module.
2. Replace the Photoconductor belt module. (See Chapter 6)
232 SuperScript 4400 — Maintenance Guide
Drum Cleaner