Brother GTX pro Instruction Manual page 200

(6) Check to see if the printed result of both sides are acceptable, and if no ink-jet droplets have been ejected, perform
a head cleaning for print heads.☞ "7-2-2. Head cleaning >>P.201"
<IMPORTANT>

If the print result shows an intermittent line, non-ejection has occurred. A head cleaning should be performed on the print
head that has a poor nozzle check result.

Even if the lines of the white-side printed result are light, since white ink is fired from more than one nozzle on the same
place, the quality is not affected.
Non-ejection occurred at the arrowed area.
Example:
Precautions to keep good printing quality/use printer over the long term
On the color side
Non-ejection occurred at the arrowed area.
Example:
200
On the white side
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