Canon Finisher-AB1 Service Manual page 281

Chapter 3
3) The aligning plate is moved to a point suited to the size of the paper.
[1]Paper
[2]Pull-in roller
[3]Alignment plate
4) The foregoing operations put the stack of sheets in order.
3-42
[5]
F-3-39
[4]Paper positioning plate
[5]Vertical path assembly
[1]
[2]
[3]
[4]