Canon Staple Finisher-AA1 Service Manual page 185

3. Adjust the angle of the paddle blade [1] so that it becomes in parallel with the line [B].
CAUTION:
There are 2 paddle blades. So do not take the wrong blade to confirm its position.
CAUTION:
Do not have the paddle blade be in parallel with the line [A] or the adjustment fails.
[1]
[A]
[B]
177
5. Adjustment