Canon Satera LBP-3910 User Manual page 70

IMPORTANT
If the duplex unit is not installed on the printer firmly (if there is any space between
the rear of the printer and the duplex unit), this may result in misfeeds.
11
If the sub-output tray is being used, open it, and if the output
tray is being used, close the sub-output tray.
12
Close the front cover.
69