2005 Roadster. Several months ago radio became eratic and now no audio. The panel shows stations and station selection and program info but audio became eratic to the point that there was nothing. Purchased used radio via eBay which I received today. Same problem. No audio altho again stations appear etc. same as I've describe above. Could there be a problem with the wiring harness?? I haven't a clue. Thanks in advance for your help.