Canon imageRunner 6020 Reference Manual Reference Manual page 446

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7-24 Finisher-F1/Saddle Finisher-F2/Puncher Unit-B1
Remove all of the jammed staples that slide from the staple
cartridge.
Return the bracket on the staple case to its original position.
Gently push the staple case back into the finisher until the
green lever returns to its original position.