Brother SC-2000 Service Manual page 73

Adjust the ends of the ribs of the shutter rear to the centers of the pinion shafts.
Set the shutter front so that there will be no clearance between the ends of the ribs
of the shutter front and those of the shutter rear, as shown in Fig. 3.68.
Shutter rear
Shutter front
Fig. 3.68
III - 55