Probably at least 5 years old. Bought it used and put it away for a couple years. Fired it up recently and I get a clicking sound out of the speaker that increases as the volume is turned up. Pulled the speaker, looked it over, all connections look good. Hooked it back up. No sound at all. Some of the other posts suggest a factory reset by pressing the 'A' button. Where is the 'A' button? My unit doesn't have one. Replace the speaker? Can I put a bigger wattage speaker in?