Make sure that two gray levers inside the back cover, one on the left-hand side and one on the right-hand side, are in the up position.
Make sure that the media type settings in the printer driver and in the machine's Paper Type menu matches the type of paper you are using.
Choose Improve Toner Fixing mode in the printer driver as follows. If this selection does not provide enough improvement, select Thicker paper in Media Type settings.
NOTE: Illustrations shown below may vary depending on your Operating System (OS).
For Windows printer driver:
Open the Printing Preferences dialog box and click Advanced tab.
Click on Other Print Options.
Select "Improve Print Output" for Printer Function and select "Improve Toner Fixing" for Improve Print Output. Click on OK.
For Windows BR-Script printer driver:
Open the Printing Preferences dialog box and click on Advanced.
Select "Improve Toner Fixing" for Improve Print Output. Click on OK.