Oki C 3400n - Manual (Page 80)

C3400n User’s Guide
80
9. Holding the cartridge by its top center with the colored lever to
the right, lower it into the printer over the image drum unit from
which the old cartridge was removed.
10. Insert the left end of the cartridge into the top of the image drum
unit first, pushing it against the spring on the drum unit, then
lower the right end of the cartridge onto the image drum unit.
Toner_replace_F5_03.eps
11. Pressing gently down on the cartridge to ensure that it is firmly
seated, push the colored lever (1) towards the rear of the printer.