Dell C1765NF MFP Laser Printer - Manual (Page 346)

344 Troubleshooting
Pitched color dots
If this trouble comes out, contact Dell.
Vertical blanks
Mottle
Action Yes No
1 Clean inside the printer and performing test print.
a Clean inside the printer by using the cleaning rod. See "Cleaning
Inside the Printer" on page 313.
b Click Print Test Page in Printer properties of the printer driver.
Is the problem recovered?
The task is complete. Contact Dell.
Action Yes No
1 Adjust the transfer bias.
a Launch the Tool Box, click Adjust Transfer Roller on the Printer
Maintenance tab.
b Adjust the setting for the type of print media being used.
Is the problem recovered?
The task is complete. Go to action 2.
2 If you use non-recommended print media, use the print media
recommended for the printer.
Is the problem recovered?
The task is complete. Contact Dell.