I could be of course way off base here, but it seems to me it's
a) not that old, I think late 80s - early 90s
b) even originally it's meant to be a budget speaker
c) It's clearly in bad cosmetic share
d) if you're looking for its value, I think it's not much. If you're looking to restore it - I think you should find a different project.
Your best bet to find help with vintage (not that this one is really vintage) is AudioKarma forums