Can I repair speaker foam?

Better to have a professional refoam them with new foam. Not sure where glue will get you. Have both pairs done while you're at it.

Refoam them yourself. It's inexpensive ($25 for a pair) and easy. I've refoamed 2 sets of speakers myself with no problems.

http://refoam.com/kits.asp

Do the following 2 things.

1) do not use the speakers, as this may cause further tearing of the foam, and then has the potential of causing the voice coil to rub against the inside slot of the magnet. Once that happens you then need a full re-cone, and
that is when things get espensive.

2) remove both midranges, and call Millersound in PA, ask for Bill. Do web search, or look at switchboard.com Mail the pair of drivers to them. You will have speakers that perform like new.

I'm not affiliated with Millersound, but I have had numerous drivers repaired by them (different sizes, different manufacturers). I have friends that have been very happy with both the price, and the quality of the work.

It sounds like you caught this early enough.