How do I clean the print head when print quality is poor?

To clean the print head using the printer buttons, load A4-size plain paper, turn off the printer, then turn it on while holding the Stop button until the power light flashes to print a nozzle check pattern. If broken lines or missing segments appear, hold the Stop button down for three seconds until the power light flashes to start head cleaning. If print quality has not improved after repeating nozzle check and head cleaning about four times, wait at least six hours without printing and then try again. (Page 64)