Do this ^^
I would get three of these non-inductive 10ohm resistors and wire them in series:http://www.parts-express.com/pe/psho...tnumber=004-10
The three resistors in series will act like a single 30 ohm, 30W resistor. In other words, it will have more capacity than the burnt resistor you are replacing. The behavior of the speaker will be the same. It will just be less likely to burn up.
I attached a before and after picture below to show how you can wire the resistors in series and place them on the board. Note that two of the connections just connect one resistor to another and do not connect to the circuit board at all. I drew them as half-circles, but you can just twist the wires from the resistors together and apply solder. Trim the excess wire and position them so that they won't touch anything metal. The other two connections (that end in a dot) connect to the circuit board just like the original resistor did.
To keep them from moving around, glue the resistors to the circuit board. This, or something like it, would work just fine:http://www.homedepot.com/h_d1/N-5yc1...atalogId=10053
Soldering is not hard. And the kind you need to do is as easy as it gets. You can do it. There are lots of videos you can watch to learn, but generally you just get the parts/wires in place, heat them up with the soldering iron, melt some solder on them, and then let it cool before you try to move the parts. This:http://www.youtube.com/watch?v=1ZjdiRxr0OM
You'll need solder, too. This will work, or you can get some at Home Depot:http://www.parts-express.com/pe/show...number=370-050
If you don't feel comfortable doing this, I bet that a friend or someone else in the band would be willing to try if you show them this thread. A first-timer can definitely do this work. It won't be hard, and you'll end up with fixed speakers and a new skill. Go for it!