Canon MG6400 SERIES Online Manual page 173

(5) Select Yes, then press the OK button.
The nozzle check pattern will be printed.
5. Examine the nozzle check pattern.
Examining the Nozzle Check Pattern
Note
Press the HOME button to exit Setup and display the HOME screen.
If the problem is not resolved after cleaning the print head twice, clean the print head
deeply.
Cleaning the Print Head Deeply
173