Regarding my NRD-515 with no audio. Trouble in the cockpit. The fellow who shipped it to me removed the muting plug from the back of the radio for shipment. I saw it but didn't know to plug it back in. I owned one of these circa 1987 and I will be damned if I remember that plug. Thanks for your help and looking forward to participating in the list with my new toy. Steve Rutledge