Well it seems clear she is owed for the currently booked shows. Screw small claims court - it's a crapshoot and some appointed non-judge will just split your claim down the middle. Hire a lawyer to send one letter demanding the $1300 plus his costs. I bet my hat that will do it.
One more thing - with a good lawyer my plan will fly with or without a written contract. I doubt they have the stomach for a fight.
And of course, you actually send a "courtesy copy" to that attorney.