Okay, so I've got this great acoustic bass. And, I've got an insane, neurotic cattle dog who insists on being loved while I am playing. Cattle dog paws the bass and makes three nice scratches (in the finish only, not the wood beneath). Is it possible to sand them out and refinish just this spot? How heavy a cinderblock, and what length of rope do I need for the cattle dog? Anybody have some tips? Thanks.