Canon CLC5151 Reference Manual page 367

2
Grip the saddle stitcher unit by its handle, and pull it out of the finisher
until it stops.
3
Pull the stapler unit of the saddle stitcher unit towards you, and then
push it up.
4
Pull out the empty staple cartridge, holding it by its left and right sides.
Saddle Stitcher Unit
Stapler Unit of the
Saddle Stitcher Unit
Finisher-W1/Saddle Finisher-W2/Puncher Unit-AG1 (Optional)
7
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