Canon MX720 Series Online Manual page 134

(10) Holding both sides of the paper output tray, gently open it.
The output tray extension will open automatically when the paper output tray is opened.
(11) Extend the paper output support.
(12) Press the OK button.
The paper cleans the inside of the machine as it feeds through the machine.
Check the folded parts of the ejected paper. If they are smudged with ink, perform Bottom Plate
Cleaning again.
(13) When the completion message appears, press the OK button.
The screen will return to the Maintenance screen.
If the problem is not resolved after performing cleaning again, the protrusions inside the machine may be
stained. Clean them according to instructions.
Cleaning the Protrusions inside the Machine
Note
To access other available functions, use the mode buttons or the MENU button.
When performing Bottom Plate Cleaning again, be sure to use a new piece of paper.