Epson AcuLaser C9200 Series - Manual (Page 147)

8. Hold cover A and Duplex Unit, and then disengage the hook on the right side.
9. Confirm that the direction of the hook is as shown below.
c
Caution:
If the direction of the hook is not correct, Duplex Unit cannot be installed properly next time.
EPSON AcuLaser C9200 Series User's Guide
Installing Options 147