Apple PC Compatibility Card - Manual (Page 48)

48 Chapter 2
Replacing the chassis and expansion card cover
23 Make sure all cards and cables are firmly connected.
24 Disengage the support arm and swing the chassis down, without pinching any cables.
Make sure the cables you connected are away from the heat sink and center
support post.
Support arm
Disengage the support arm from the hole on the floor
of the bottom chassis by lifting up on the support arm.
Gently swing the top part of the chassis down until it rests securely on the bottom chassis.
Be sure that you don’t pinch any of the cables between the top and bottom parts of the chassis.