Atari SLM804 Series Owner's Manual page 12

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4. Holding the drum by its handle, place the drum in the well toward
the back of the printer. Be sure that the drum axle fits in the two
slots on either side of the printer.
Slot
5. Untape the clear plastic tab from the top of the toner cartridge.
7
Pull the tab straight out and to the right while holding the toner
cartridge top in place. This releases the toner into the hopper.
Make sure that you clean off any toner that drops onto the
contacts below.
Contacts