Brother GT-3 Series Service Manual page 300

(3) Pass the Plastic Cover between the PCB and the metal plate.
(4) Insert the convex part (4) of the Plastic Cover into the hole (5) on the Damper Case.
(5) Insert the side of the Plastic Cover into the bottom of the Print Head Knob.
7.
Tighten the screw on the top of the Print Head.
(2)
(3)
(1)
(4)
(5)
GT-3 Series
6. Replacing Parts
291