Brother GT-3 Series Service Manual page 150

Back side
3.
Mount the two Ball Bearing Radial 688ZZs (4) and the two Retaining Rings (5).
<Note> Prepare new Retaining Rings for replacement, you cannot reuse.
( 7)
4.
Confirm that the R Pulley Assy (6) can rotate smoothly.
( 7)
5.
Mount the Pulley Base (7) and the Platen Belt, and adjust the Belt Tension. (Refer to "6-1-5. Adjusting
the tension of Platen Belt and Reduction Belt".)
(5)
(4)
(6)
GT-3 Series
6. Replacing Parts
141