Brother GTX-4 Service Manual page 301

(18) By following the procedures mentioned below, mount a new print head on the carriage.
a Insert the rearward end of print head into the carriage.
s Push with force in direction s so that the illustrated part (a) makes contact with the side of the metal plate of the print head.
d Lock the print head in place.
<IMPORTANT>

Make sure the illustrated (a) part is in contact with the side of the metal plate.

When re-installing the print head with ink refilled, care must be taken not to mistake white for color.

When placing the print head in position, be careful not to move the carriage as much as possible. Your hand may be caught
in the carriage and injured. In addition, the tubes may be rolled together possibly damaging them.

When you mount d, push it down from the top. Otherwise, you may get your finger caught in it and get injured.
<TIPS>

If the print head is not inserted sufficiently, the part as illustrated in (b) could come into contact with its bottom surface, which
in turn may result in poor printing. Please insert the print head as far as it can go.
①
②
Print head
①
(b)
Print head
(a)
Disassembly / Replacement / Adjustment
6-110
Carriage
③
X0073
X0129