Running a 893 corn head.   Having problems with the feeder house drive gearbox drive belts and pullys getting BAD hot.   Belt slips, will not hold the head speed consistently.   Has the HD high capacity feeder house drive not the high torque version.   Belt is tight.   Sheave gap is correct.   Upper two bearings have been replaced, one was going bad, thought that was creating the heat, but still gets hot.   Assuming the heat is from the drive belt slipping but I can NOT figure out what is wrong.   Any thoughts or ideas ?