Canon NP6551 Operator's Manual page 194

Close the cover and push the duplexing
3
transport unit back into the main unit.
When the unit is pushed in as far as it will go, a
tone sounds.
After removing all the jammed paper, close the
4
front door.
When "Press the Start key" appears in the touch
panel display, press the
remaining copies.
MEMO: ●
If the paper jam message remains in the display,
follow the directions in the display and check again
for any jammed paper.
6-20
key to make the
Start