Xerox Phaser 8400 Service Manual page 268

7.
Remove left and right printhead restraints. First remove the screw, then pull
inward towards the printhead, then lift up and slightly toward the rear of the
printer to remove (see figure below).
s8400-133
Note
Adjust printhead position as required to remove the right restraint.
8-16 Phaser 8400 Color Printer