Brother MFC9100C Service Manual page 117

3. ADJUSTMENT
The adjustment jobs should be done on a flat, plain surface.
3.1 Purge Unit Front-to-rear Adjustment
If you have removed the purge unit, you need to adjust the position of the purge unit relative to the
carriage rail by using the purge unit adjuster.
If you have removed also the carriage rail or carriage ASSY, it is recommended that you first
adjust the head-platen gap (see Section 3.2) for accurate gap and then proceed to this purge unit
adjustment.
Purge unit adjuster
The purge unit adjuster is shown below.
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