It was just one of the speakers and both of the woofers were not working. The other M80 works just fine.

I will try the bare wire and see if that does make a difference. It does make me nervous to unscrew anything on those speakers in fear of not being able to put them back together correctly.

As far as getting in touch with the previous owner, he promptly responded to my email and said he would see if he could help out in any way.