Apple Power Macintosh 7600/200 Series - Manual (Page 127)

11 Replace the chassis by disengaging the support arm and gently swinging the chassis
back into place.
Support arm
1 Disengage the support arm from the hole
on the floor of the bottom chassis by lifting
up on the support arm. 2 Gently swing the top part of the
chassis down until it rests securely
on the bottom chassis.
127 Installing PCI Expansion Cards and Additional Memory