My DB recently developed 2 areas where the strings buzz on the freatboard. I think it may be due to slight warping - I can't see it, but the buzz is clearly at the same position for each string. I talked to the shop I purchased it from, and they suggested that I try to sand the fretboard, and that would get rid of whatever is causing the buzz. To be honest, that frightens me a bit. Would'nt even know what grade of sandpaper to get. Any suggestions ?