Bob, thank you so much for your post. You just saved me $500.
I'm not very handy and I usually have very bad luck with do-it-yourself projects, but this one worked like a charm.
Although I couldn't see any tears in the paper part of the speaker, I went ahead and applied glue to the margin between the paper and the foam rubber. No luck. Then, I glued the outermost space between the foam rubber and the metal housing and it worked!
I admit I made a mess of the glue with stringy masses of glue everywhere. But, no matter. My subwoofer is back to life and working perfectly.
To those of you who are do-it-yourself challenged: If I can do this anyone can.