Xerox 3450B - Phaser B/W Laser Printer Service Manual page 140

3.
Remove 9 screws and slightly lift the Duplex Assembly from its mounting
location.
Note
The screw that secures the ground wire to the back edge of the assembly is
the short machine screw.
Caution
Do not attempt to remove the Power Supply Board Assembly from the
printer until you first disconnect all 5 connectors.
Service Parts Disassembly
s3450-179
8-43