After the nozzle check pattern has been printed, examine it.

Check if there are horizontal white streaks in the pattern (1) and/or pattern (2).

If there are horizontal white streaks in the pattern (1):

Cleaning the print head nozzles is required.
 

If there are horizontal white streaks in the pattern (2):

Cleaning the print head nozzles is required.

(A) Good (no horizontal white streaks)

(B) Bad (horizontal white streaks are present)

If streaks are present or if a color is missing entirely, clean the print head.  Also, remove the ink tanks and ensure that no packing material (orange tape) is present.  If packing material is on the ink tank, remove it and print a nozzle check again.

If a print head cleaning does not improve the results of a nozzle check, clean the print head deeply from a computer.