The same thing happened to my os46la on its first day at the field. I used a piece of 1 inch aluminum conduit and turned it in a lathe to fit inside the muffler and heli-arced a cap on the end. I drilled two holesin it one for the mounting screw and the other angled back for the exhast gas. I used 4/40 threaded rod to attach it and double nutted it. It is almost as quiet but has a deeper sound. If I ever replace it the muffler for a Tower Hobby 46 BB will fit it for $14.99.