i think we may have found the problem. you guys mentioned belt slipping,i think that is it.i am going along at a steady speed in 175bu. corn and then my yield monitor falls immediatly to 110 the same time my pacer slams back to slower,then i slow to a crawl and it takes forever to catch up. i will replace the 3 ribbed drive belt and theclean grain belt and the fan belt in the morning. THANKS to everyone with help and advice. i will let you know if this cures it,or if i have any other trouble.