Brother GTX-4 Instruction Manual page 147

Case of 16X21 platen
As an example, the case where the platen's height is set to the lowest position is described below.
(1) Detach the platen from the main unit of the printer.
(2) Remove the platen fixing lever, platen height adjustment lever and collars.
(3) Loosen the knob that fixes the platen bearing in place.
0 to 0.4 in. (0 to 10 mm)
Knob
Platen height adjustment lever
Collars
Platen fixing lever
Platen bearing
147
Basic printing procedures
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X0165
X0103
X0104