Canon MX720 Series Online Manual page 117

Make sure that the machine is on and then click OK.
Click OK when the confirmation message appears.
Print head deep cleaning starts.
Important
Do not close the paper output tray until the deep cleaning is complete.
4. Complete deep cleaning
The Nozzle Check dialog opens after the confirmation message.
5. Check the results
To check whether the print quality has improved, click Print Check Pattern. To cancel the check
process, click Cancel.
Important
Deep Cleaning consumes a larger amount of ink than Cleaning.
Cleaning the print head frequently will rapidly deplete your printer's ink supply. Consequently, perform
cleaning only when necessary.
Note
If there is no sign of improvement after Deep Cleaning, switch off the machine, wait 24 hours, and
then perform Deep Cleaning again. If there is still no sign of improvement, the ink may have run out or
the print head may be worn. For details on the remedial action to be taken, see "Ink Is Not Ejected."
Related Topic
Use Your Computer to Print a Nozzle Check Pattern