Tim Isaac demonstrated how he pulls out damaged tubes. Cut a section out of the middle of the damaged tube and drill some holes in the stubs to hold bungee cords between the stubs (not a lot of tension, just enough to exert an even pull on the stubs). Heat the joint at one end of the stub with a big rosebud tip (or two, if you have another pair of hands to handle another torch). Heat the joint evenly and when the braze liquifies, the bungee cords pull the tube out of the joint with minimal distortion. Repeat on the other stub. Clean out the sockets and braze in the replacement tube.