Brother GTX-4 Service Manual page 300

(17) Release the lock by pulling (a) part toward yourself, and take out the new print head from its case.
<IMPORTANT>

When removing the print head, be careful not to touch the nozzle surface at the bottom of the head. Otherwise it may cause
poor printing.
<TIPS>

Sometimes, you may find it hard to remove the print head when you try to open the lock of (a) part. If it is hard, use both
hands to remove it.
Print head
(a) part
Disassembly / Replacement / Adjustment
Case
6-109
X0069