Tested all the intercom wiring and found the Mic. jack wiring on both pilot jacks reversed. Pins 10-23 on pilot Mic. jack reversed and pins 16-3 on co-pilot Mic. jack reversed. The video on Steinair's web site " Headset Jacks " was very informative. Once I understood the schematic ( mainly the direction of the plug ) and Tip, Ring, Barrel it was quite straight forward. It was a very quick fix and I'm glad I found the issue before installation. I connected the control column PTT buttons and they both work when pushed.
