Wow, John, that's a bummer. How did it happen?You know how it is with machines. If something is damaged, you can limp along or you can rebuild. If you limp along, you can't reach full potential, but sometimes that's what you must do. And if you don't need full potential, then there's no problem with it.
But I'm sort of picky about stuff like that. If I have the money, I want to do a whole rebuild. You can probably get those reconed pretty inexpensively, so I'd suggest that as your best option. It's the only way they'll be 100% the way they're designed to be.
Then again, if you can't get them reconed right now, by all means, give them a bead of diluted white glue or something to strengthen the damaged area. Keep the glue off the surround 'cause the glue will dry rigid and will cause folding of the fibers at the edge of the glue seam. I've done this kind of repair a lot on very old speakers in things like tube radios when the cone is damaged but I don't want to recone.
I usually put white glue on my finger and have a cup of water nearby to dip my finger in to dilute the glue. I then apply the diluted glue onto the damaged area, lightly pressing the cone to saturate the fibers with diluted glue. Use as little as possible along the crease, but try to surround the crease along its path. When I have used what I felt was enough to unbalance the cone, I put equal amounts in places around the cone to rebalance it somewhat. I usually do this in three spots, 120o apart. But dried glue isn't very heavy actually, and this probably isn't necessary in most cases.
So tell us now - How did it happen? Inquiring minds want to know.