Apple LaserWriter 12/640 PS - Manual (Page 119)

4 Open the top cover of the printer.
5 Remove the paper cassette.
6 Grasp the top and front parts of the side cover and pry gently to free the tabs from their
receiving slots.
7 Pull the side cover off.
Lift the edges of the side cover up
and out, then pull the cover off.
119 Installing Options