Roland Advanced Jet AJ-1000 Service Notes page 197

Move Head Carriage over several times in a whole width and
5
check the position of the belt on Drive Pulley.
The proper position is that Belt is located in the center of
Drive Pulley shown in the figure.
Rotate Adjustment Screw clockwise (to the direction to
tighten) when Belt is in the upper position from the center of
Drive Pulley shown in the figure.
<Front View>
1.0mm
OK
NG
4-50
Screw 3
Screw1, 2
D r i v e S h a f t
Support
Adjustment Screw