We have all tried to sand the ends of the bade clamps, but for me without too much success. I saw a posting on you tube where a guy put a nut on the set screw of the clamp--with just the end showing , rub the bolt across some sand paper--My EX-21 is having troubles so I ordered a new set of clamp screw. I put a #6 metric bolt on the set screw (old one), ran it over some 80 grit and the set crew is nice and flat and the clamps work great--sooooo if you are having trouble try this. better 10 cents than $12---Richard aka thumbs