Canon MP490 series On-Screen Manual page 72

For (B) (lines are missing or horizontal white streaks are present) in (1) or (2) , or in both (1)
(2) :
(1) Select Also B and press the OK button.
Clean the Print Head. The cleaning confirmation screen will appear.
Select Yes and press the
(2)
The machine starts cleaning the Print Head.
See Cleaning the Print Head
button.
OK
.
and
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