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 ? :confused:

Put a long straightedge (metal ruler or stable bar) against the fingerboard; it may betray the high spot(s). Any grade of sandpaper can be used, 60-100 will remove wood quickly, 150-200 is less aggressive -- just use 400 grit or so for the final smoothing of the fingerboard. And take it slow.

Bob All Hail is on the mark, per usual. And:

20 years ago my old maestro said about guitar FB, "The first 200 are the toughest." He was right. I've dressed hundreds of guitar FB, and I won't dress my own double-bass FB. The reason is that some curve is desirable, but too much is bad. How much? Where? Since I don't know, I pay those who do.

If you've decided to give it a try: If you're just working on a small high spot, 320 grit might be the paper to start with. Use a sanding block -- don't just use your thumb, or you'll dig a deeper hole. To polish the board, go to 600 grit, then use 0000 steel wool with lemon or mineral oil. This will really make the wood gleam for a good long while.

Again, echoing Bob AH: When removing wood, "Don't forget this fact, you can't get it back." Good luck!