Apple Performa 6400/180 - Manual (Page 161)

Take Apart Feet - 64
2 Press in two of the
plastic tabs on a foot.
3 Tilt the foot toward the
third plastic tab to clear
the slots and remove the
foot.
Replacement Note:
There
is a raised plastic guide post
that fits in a notch on the
bottom of the computer. Be
sure to line up the guide post
with the notch.