My box call is off note. I think it has worn down, and now doesn't seem to have the right pitch. Can I sand it down a little? If so, with what sand paper, and which direction? Thanks.
Sand the edge With the grain so that it slants a little to the inside of the box. Use a fine grit so that you don't takt off too much at one time.
You might also try adjusting the screw in the lid. I usually get the best sound when the lid is set to strike at the top of the arch. Make small adjustments. Turn the screw 1/8 turn at a time and keep up with how much you've turned it.