I hate to suggest this, but it might be the capacitors. I have two extra junk condition IFU-30s, and one of them has the same snowy picture as you describe (plus a bit staticky sound). I don't think the interface units are as prone to capacitor failure as the Duos, but it's a possibility. Especially if you have one of the newer IFUs, that doesn't say IFU-30 on the cover.