Canon MG8100 series On-Screen Manual page 982

Check 5: Remove the foreign object in the Cassette.
Check 6: Make sure that there are not any foreign objects in the Rear
Tray.
If the paper tears in the Rear Tray, see
If there are any foreign objects in the Rear Tray, be sure to turn off the machine, unplug it from the
power supply, then remove the foreign object.
Check 7: Make sure that the Inner Cover is closed completely.
Paper does not feed properly if the Inner Cover is even slightly open.
Overview of the Machine
Check 8: Clean the Paper Feed Roller.
Routine Maintenance
Note
Cleaning the Paper Feed Roller will wear the roller, so perform this procedure only when
necessary.
Check 9: If two or more sheets of paper feed from the Cassette at once,
clean the inside of the Cassette.
Paper Jams to remove it.