If you ever need to pull or replace a cockpit
avionics box, you need to remember this.

Boxes are fixed in the panel in one of two ways:
1) A jacking screw.
Example: AT-50B Transponders have a front panel
allen head screw that goes clear
through to the back,where it locates a fixed nut
in the mount unit.

This box is removed by rotating the screw
counter-clockwise many turns.
~OR~
2) An allen head screw that threads a rotating flag
that turns out into a recess near the front located
in the case.
Example King KX-175B NavComm

If you rotated THIS allen screw several turns, you about
guarantee wrecking the radio: a known mechanical gotcha
on an otherwise excellent radio.
The trap is that the box may be stuck in place by its
mounting case, so the temptation is to suppose the
securing flag is still "out". The knobs are jiggled
sidewards to release it if possible.
Otherwise the front panel is CAREFULLY levered away
from the case.

Brought to you by the school of hard knocks.

Brian W