Roland VersaEXPRESS RF-640 Service Notes page 146

Put the Encoder Scale in between the Encoder Plate and the
5
Guide Rail.
Then, fi x the right end with the plate, and hook up the spring
on the left end.
Make sure that the Encoder Scale is in place.
Do not loosen or tighten the screws fixing the
Encoder Plate.
Move the Head Carriage to the whole width of the machine,
6
to make sure that the Encoder Scale doesn't make contact
with the Encoder Module, and also Encoder Scale is between
the slit of the Encoder Module.
Carry out the [4-5 LINEAR ENCODER SETUP].
<Closeup image of Encoder Scale and Module>
Encoder Scale
Module
3-72
Encoder Scale
Guide Rail
Encoder Scale
Encoder Plate
Screw
Spring
Encoder Plate
Plate