Canon Color imageCLASS MF8170c Basic Manual page 33

Push down the plate of the paper cassette to lock it.
2
CAUTION
Do not touch the lock release levers located on the right and left sides of the
paper cassette when the plate of the paper cassette is locked. The plate may
snap forcefully if the lock is released and may result in personal injuries.
Lock release lever
Lock release lever
Hold the lock release lever of the rear paper guide and slide the
guide to the mark indicating the subject paper size.
The paper size indicated on the paper guide should be aligned with the mark.
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