Xerox 3400N - Phaser B/W Laser Printer Service Manual page 60

Fig. 1
Fig. 2
Fig. 3
P3400-036
Do not bind the registration actuator against the print engine
controller board. Ensure that the registration actuator moves
freely.
When replacing the main cover, be careful not to snap off the
Multi-Purpose Feeder actuator.
Removal and Replacement Procedures 49