that took care of it, i decided that if I started sanding and ran out of block, i'd have to cut and replace anyway, so I broke out the razor plane, then started sanding, slowly. thank goodness for 3M "sandblaster" sandpaper, the stuff works like a dream, chews through balsa faster than my black lab, and leaves a perfect finish. I used a square of 100 grit glued to soft foam, and started with "short strokes" right on the high point, untill it was nice and smooth, and about 1/2" of dust on the work table.