Check around, there are many companies that do re-foams of the surrounds. Check with a couple high end audio dealers near you. Better than replacing the woofers with different kind, which would probably change the sound of your speakers. (Maybe better ?? but who knows?)
Woofer Problems
I have a 16-year old pair of Goetz MS3 speakers, which have a 15" woofer. I just took the grills off for the first time in months and noticed the rubber-like edge around the subwoofer has just crumbled! . . . on both woofers (altho one was way worse that the other.) Do I need to replace the subwoofers or can they be re-coned? Do reconed speakers perform equivalently to new ones? Any recommendations for companies that do this kind of work? Any responses to my email address (markwhite02@home.com) would be appreciated. Thanks, Mark