Looking for advice on comms in my 2009 T182T with G1000. I have an intermittent autonomous transmit. It occurs without depressing the push-to-talk buttons. Of course, this blocks reception and blanks all others trying to transmit on the same frequency. The transmit is instantaneous but can go on continuously. Two shops have tried to fix it. The PTT buttons have been replaced, wiring has been inspected for shorts, the problem remains. I appreciate any ideas.