smaller sieves will help 1/8, change pre sieve first, thats the cheapest, are sieves measuring the same on adjustment indicator, both top and bottom, gotta remember sure its handy to adjust sieves from cab, hmmm, they git full of sh't, bends the heck out of them, i would start first off, open sieves wide open all of them, clean crap out, open sieves wide open, then close to 1/4" with rear switches, go in to pro 600 monitor and calibrate, scott