Canon DADF-M1 Service Manual page 42

Chapter 2
The track of the slide guide is given a groove so that the slide may stop at specific default sizes. Some sizes, however, are extremely close to each other, possibly
causing the slide to stop at the wrong point. To make sure that the slide stops at the correct stops, the slide is provided with a positioning roll [1], which restricts the
stops as follows:
2-20
ADF controller PCB
Slide guide
(rear)
Gear
Marking on slide guide
positioning roll
A4R
INCH
PI3
VR1
Slide guide
(front)
F-2-20
T-2-5
Slide guide stop position
Side with 1 groove Slide with 2
grooves
A4R A4R
LTRR
LTRR A4R
LTRR