Canon LBP6780x Manual page 867

(6) Inside the front
cover
Cleaning the feed roller may prevent frequent paper jams.
"Cleaning the Feed Roller"
When you use thin paper (60 to 74 g/m²), setting [Paper Type] to [Plain L] and [Special Print Mode C] to [On] may prevent
frequent paper jams.
"Configuring the Printer Driver and Printing"
[Special Print Mode C] can also be set using the printer's control panel.
"[Setup] Menu ([User Maintenance] Options)"
<Front cover>
"Clearing Paper Jams (Inside the Front Cover)"