Brother GTX-4 Service Manual page 224

(10) Remove the screw (one) and two hole bolts fixing the cover UL and detach cover upon lifting its rear portion.
<IMPORTANT>

Always remove cover L first, then detach cover UL.
(11) Remove the three hole bolts on tension adjustment mechanism and detach tension adjustment mechanism.
(12) Detach pulley and carriage belt from tension adjustment mechanism.
Carriage belt
10
11
Pulley
Disassembly / Replacement / Adjustment
Cover UL
10
6-33
11