Canon imageRUNNER 6570 Reference Manual page 431

5
Change the paper drawer's size plate to match the new paper
size.
6
Gently push the paper drawer back into the machine until it
clicks into place in the closed position.
CAUTION
When returning the paper drawer to its original position, be careful not to
get your fingers caught, as this may result in personal injury.
Size Plate
Paper Drawers
8
8-9