Jay, you know better than to even hope for that. They quit using
mechanical switches. It probably is a small and very expensive
electronic replacement for a switch.

Actually, a friend of mine had the identical thing happen to his radio.
So this guy took his radio apart yesterday, figuring "What do I have
to lose?" -- and found a cracked 25-cent plastic gear. It was cracked
cleanly down to the shaft, in a nice, straight line.

Whenever that part of the gear mated with the tuning shaft's gear, the
shaft would slip, as the broken gear "flexed" away from the other gear.
This rendered the small frequencies (the ".075" part) unchangeable.

Of course, for an avionics shop to get at that gear would require
dismantling dozens of other little gears, gizmos, and what-nots, to the
tune of several hundred dollars in labor. Since the radio itself (an
old, out-of-production, Com-only Narco 120) was worth MAYBE $200, my
friend sat down with an A&P friend, and postulated a fix.

First, he discovered that he could tune the radio by pressing the
broken gear up against the shaft gear with a screw driver while turning
the knob. With trial and error he re-aligned the frequency in the
window to be accurate, by tuning it to his local AWOS frequency.

Then, he set the radio on end, so that the broken gear was horizontal.
By carefully placing a piece of scotch tape on the bottom of the broken
gear, he created a "plate" for glue to build up against. He then VERY
carefully packed JB Weld into the tiny break in the gear, filling the
space down to the scotch tape, and being careful not to "fill in" any
gear teeth.

JB Weld completely dries in 15 minutes, so after 12 minutes it has set
up firmly, whereupon he carefully removed the scotch tape. He then
carefully "packed" the stuff down so that any excess wouldn't interfere
with the gear teeth.

He reassembled the radio, slid it back into the panel -- and left it to
dry. JB Weld reaches maximum strength in 24 hours, so by now it should
be as good as new.

This might buy the guy a few weeks, or it may last forever. Since his
radio is used as Com 2, primarily to listen to AWOS and/or ground
control, he doesn't use it much -- and now he'll be tuning those small
numbers VERY carefully, indeed.

My friend is a very smart guy.

:-)
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"