Scotch Brite is all you need, you don't need to use sandpaper, the scotch brite will take off the old stuff that's all you want. Did you figure out if you have a two-sided box or one? The screw, don't turn it more than a quarter turn either way, if it doesn't get better, turn it back to the original position. It is hard to yelp on the hen side because of the positioning of your hand and moving it left to right for right handers. The right side of the box, I use it to make a jake sound. I'll yelp a few times then make a funky sounding gobble with it. That is later in the morning or if I have a tom holding up on me. I can also make a very deep cluck with it after a worbled gobble. This is because a lot of young toms are still learning a good gobble, but like most on here, I have also killed some old toms that had an awful sounding gobble. Those boxes are fantastic at making a gobble. If you want to tune it, use scotch brite to get the old chalk off ---- use blue chalk --- use small rubber bands that aren't tight, they need to be a little loose, the tight rubber bands pulls the paddles against the top of the box too hard ----- One more old trick, use a couple pieces of paper towel stuffed the length of the box, this will give the call a more throaty sound, kind of like a good muffler on a Vette vs. a fart can on a ricer.