There is a headphone jack on the back, have you tried a set of headphones to verify it's the speaker and not something else? Have you tried it on all radio bands and it doesn't work or does it just not work for certain modes? Does it give any static out on any of the bands? The thumbwheel volume knob could also be a problem, have you run that back & forth in case it's dirty? Any further checking will likely require opening it up and looking for ways to test.