Looking for help, I use my Pro-2042 sometimes to feed a stream. Lately I hear a pop every six seconds over the feed? Tried changing all cords involved and stopped using 13.8 VDC input and plugged in the A/C cord. All attempts no joy? There must be a cap or something going bad? Every 6 seconds pop over the the audio tape out not on the speaker though. Anyone have ideas what it could be?