Brother MFC Series Service Manual page 285

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 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
No
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