Brother GTX pro Instruction Manual page 145

(8) Use the platen fixing lever to secure the platen temporarily.
The number of collars and the position of screw hole for the platen bearing differ by the height of the platen
adjusted.
<TIPS>

If you are setting the platen's height to the lowest position, remove all the collars and fix the platen bearing at its highest
screw hole temporarily.

If you are setting the platen's height to the middle position, attach one collar and fix the platen bearing at its middle screw
hole temporarily.

If you are setting the platen's height to the highest position, attach two collars and fix the platen bearing at its lowest screw
hole temporarily.
(9) Tighten the knob to secure the platen bearing in place.
<TIPS>

Align the center of platen fixing lever with the position as illustrated in the figure below, and secure the platen bearing in
place.
Platen bearing
Knob
(10) Insert the platen to be used and tighten the platen fixing lever.
Platen fixing lever
Platen fixing lever
Knob
145
Basic printing procedures
Platen bearing
Platen bearing
Center
position
alignment
Platen fixing lever
X0271
X0272