Brother DCP-J552DW Service Manual page 305

Selector 7: Unidirectional print (for higher print quality)

The machine prints bidirectionally by default. To get higher print quality, set this selector to "1"
to switch to the unidirectional print mode. In this mode, printing is performed only when the
head/carriage unit travels from left to right. Note that the unidirectional print mode sacrifices
the print speed.
Print object
Print FAX message received
Copy
Print from PC
Print from memory cards or via PictBridge
Print memory card index or PictBridge index
Print a list
Printout of Test Pattern
Selector 8: Improvement of paper feeding reliability

Setting this selector to "1" improves the paper feeding reliability, sacrificing the print speed.
Unidirectional print
Yes
Yes
No
Yes
Yes
Yes
No
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