Hello I am having issues with a GMA 240 audio panel. It’s connected to a single GNS 430, single set of phones and mic jack per the installation manual (no brained) However as soon as it turns on, it goes through its self check (all lights go on and settle at the selected output) but the sound is heavily diminished. With the audio panel off, the GNS 430 radio sounds good and loud with full range of volume control. With the panel on, the sound is barely audiable. It feels as if the amplification through the panel has failed. Any suggestions and ideas? Any shop can maybe bench test it to see if the GMA itself is bad or not? I don’t want to send it to Garmin for a flat $600 fee. Thanks