Brother GT-3 Series Service Manual page 149

6. Replacing Parts
Assembling
Front side
1.
Mount the two Ball Bearing Radial 688ZZs (1) and the two Retaining Rings (2).
<Note> Prepare new Retaining Rings for replacement, you cannot reuse.
(2)
2.
Confirm that the F Pulley Assy (3) can rotate smoothly.
(3)
140
(1)
GT-3 Series
(1)
(2)