Brother MFC-J3520 Service Manual page 157

(24)Remove the CR timing belt from the Gear of the Carriage motor ASSY.
CR timing belt
(25)Loosely tie the CR timing belt in a bundle on the Head/carriage unit as shown in
the figure below.
(26)Pull the two Locks in the direction of the arrow to release the position.
Head/carriage unit
CR timing belt
Fig. 3-17
Head/carriage unit
Fig. 3-18
3-37
CR frame ASSY
Gear of the Carriage motor ASSY
Lock
Confidential
Lock