Each year I always start with the initial setting recommended by MF, and then adjust as necessary, as conditions always vary from year to year. My reference is a single laminated MF sheet entitled PROFIT-BOOSTING ADJUSTMENTS FOR MASSEY-FERGUSON COMBINES, publication number 602 AG_5-75_10-5 and C602_570-5-2.  It covers adjustments for small grain, soybeans and corn.  I've copied the initial settings for corn:  Elevator, drum height: top; heavy corn or trash, down one hole for average crop.  Concave: remove filler bars from wide spaced concave, or remove every second wire from narrow-based concave.  Concave Setting: front: 7_8" to 1-1_4" Rear: 3_8" to 7_8"  Cylinder Speed: 485 to 650 r.p.m.  Rear Beater: Use spike-tooth beater blades for better handling of corn shucks and other trash.  Grain Pan Screen: Install 3_16" or 1_4" screen to remove dirt, fine chaff and snow before material passes onto shoe.  Triple Screen Shoe:  Top 1-5_8" screen set to 9_16" ,  Middle 1-1_8" screen * set to 9_16",  Bottom front 13_16" screen set to 3_8" (or 5_8" diameter round hole screen) ,  and bottom rear 1-5_8" screen set to 5_8".  (* relocated from top position).  This implies that you replace the top screen with a 1-5_8" screen, and move the top screen to the middle position.  Fanning Mill: Minimum deflector clearance in front. Direct most of air toward front of shoe - adjust rearward if trash starts piling up on back end.  Install high speed fan kit for better cleaning; fan shields to keep out trash. (MF 410_MF510 Grain only).  Returns Cylinder and Rethresher: Remove all channel-type concave sections to avoid cracking corn.