FujiFilm PROFECT CS Service Manual page 793

3.
While pressing the scanning optics unit in the direction indicated by
the arrow in the figure, retain the subscanning unit.
011-202-08E
09.30.2009 FM5540
REFERENCE
By pressing the two positioning brackets and the knob of the scanning optics
unit against the frame of the subscanning unit, the scanning optics unit can be
installed in place.
CR-IR 363 Service Manual
MC-304
MC-304