Canon Staple Finisher-AA1 Service Manual page 64

Note that the staple-free binding unit is shifted by the stapler shift motor (M114) to the front or rear in sync with the stapler unit.
When stapling by the stapler unit is taking place, the staple-free binding unit is stored in the rear.
Staple-free Binding Motor (M116)
Staple-free Binding Motor
Clock Sensor (PS130)
Staple-free Binding HP Sensor (PS129)
Because the staple-free binding position is only rear 1-point binding, the binding position for the printing is changed by the
combination of the printing image rotation control and face up/down delivery function.
The relations between the direction of the printing and the binding position are described below.
Binding Position
A
Paper
Staple-free Binding Unit
Rack Gear
Stapler Drive Belt
Binding Position
56
2. Technical Explanation
Stapler Unit
Stapler Shift Motor (M114)
Paper
Staple-Free Binding Unit