Brother HL-3450CN - Manual (Page 159)

CHAPTER 6 OPTIONS
6-3
6. Check the two alignment pins on
the Lower Tray Unit. Use two
people to lift the printer and
place it onto the Lower Tray Unit.
Be sure to use the handholds
located at the bottom four
corners of the printer. Check to
ensure that the pins align
correctly into the printer.
Fig. 6-4
7. Remove the Connection Cable
cover.
Fig. 6-5
8. Securely connect the printer and
the Tray Unit at the rear with the
metal lock plate and the screw.
Undo the screw a little to release
the lock plate, hook the metal tip
into the printer, and then
retighten the screw.
Fig. 6-6