I need advice on a JA-S11G that I've picked up. I'm getting some sound through to the speakers but at such a low level that I can only barely hear it with the volume jacked up and my ear next to the speaker. I've blown the dust out and checked the fuses, which appear to be OK, but I don't know what to try next. I have a multimeter but I'm new to these circuits and I don't want to cause damage. Any suggestions will be gratefully received.