Oki ES9170 Quick Start Manual page 43

Saddle Stitch Unit of Saddle Stitch Finisher (MJ-1033)
Open the left cover of the Finisher.
Take off the staple cartridge.
Pull out straight the seal bundling the staples.
Install new staple cartridges.
Close the left cover of the Finisher.
Replacing Staple Cartridge
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