Greetings! I have a Craftsman Router Model 315.17381. My Grandpa gave it to me before he passed away. When I tried to use it, I heard a chattering. One of the mmetal pieces on the armature where the brushes ride is missing. So i am trying to find another armature or an unwanted router of the same type I can purchase. Does anyone know where I can find one? I'm think that this request is futile, but I have to try. Sears parts says it is unavailable. Thanks!