I could be north or south depending on the way I go.
Please, please don't set fire to it. I think if you do the things I suggested we/you could be on the right track.
Put aside a day to have a look though.
On reading your initial enquire it would appear that there is a broken wire either side (one or the other) of the din plugs as each of those separate pins is for the head set on talking, listening etc. it is just
a matter of finding which wire is broken, now before you do anything do you know someone with a wing that has a CB, headset, if so plug their helmet into your system and see if they have the same problem as you, and if not then the problem is in the area of the din plugs.
It's not a major, the more we can rule out the closer we get to solving the problem.