I think I've narrowed this down to the nut itself. Here the sitch: 5 string bass, the lower four strings are perfect, but the G string buzzes when I hit it hard in just the right way. If I "pop" it vertically, like when I'm slapping, the sound is fine, but if I yank on it like when I'm hitting the string really hard fingerstyle, it buzzes at the nut, kind of a flabby sound. It sounds like the witness point isn't quite making a good solid connection. Am I on the right track here, do I need to replace the nut? What specifically is the problem, does the groove have to be dug deeper, or is the groove "too deep" already? Is there any way to fix it without buying and installing a new nut?