If there is about 7.2 volts dc at the speaker and it is not working-it's the speaker. Easier way to check is with a known working speaker. The radios themselves are pretty sturdy-most of the time is is the speaker. Doesn't have to be completely dead to be bad either. Mine would work like a road crew (no offence to road crews given) 1/2 hour on, 1 1/2 days off.....

 

I got a buddy that's an electronic tech and that was almost his wording exactly (not the road crew part lol)...try a known working speaker to see if it's functioning. I just dislike the thought of pulling both rear door panels just to try that but I guess on the bright side, that's free and relatively easy to accomplish.