What have you got to lose ?
I would not hesitate to open it up and check, but I would first suspect those old school volume & squelch sliders noisy they can be with the wearing of time, if they make a horrible screach out of the speaker you know two things , the speaker works , the sliders need contact cleaner , available at an electronic parts supplier, as would be a replacement speaker, try the ususal tune into a known carrier if available in your area aka weather broadcast 162.4 lets say and listen for audio could be the 10 freqs that are in there are all silent ? not a waste of 20 (perhaps a savy high school kid could get er going if it turns out to be not the obvious)