How do I get my stereo speaker to work again?

I have a 1991 Sony component system. 2 large, 3 way floor speakers and some surrounds. One of the large speakers puts out good sound, but the other sounds garbled and very muted. The speaker components are in excellent condition. No dry rot or anything like that. I know it's the speaker because it will not work no matter where I plug it in. I'm wondering if the internal wiring could be the problem since the speaker wire is brand new. Please help me.