Sharp AR-C250 Operation Manual page 139

Insert the staple box into the stapler unit until it clicks in
5
place.
Push the finisher toward the copier and latch it in place.
6
CAUTION
Use caution while latching the finisher into place.
To prevent pinching your fingers, do not place your hand or fingers
on the release lever while moving the finisher toward the copier.
FINISHER (AR-FN4)
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