Be sure the idler is moveing freely. If it is the variable belt slipping, stretch in the belt should be taken up by the tightner system built into the variable pulley system. Either system should compensate for belt stretch.
this time...have a look at the belt if it has been burnt or the sides are glazed spend the money and put it in the spare"s department and put a new one on it will get you out of trouble you will find a new belt will fix the prob good luck
thanks guys....guru i done has you said and it worked perfect thanks for the email it helped me alot i have noticed and followed a few of the postings made by you.. you seem to know the way around harvesters well both red and green has for the conola loss tray etc this has made life a lot easier thanks again for the help....THISTIME