we've got a 1987 john deere 6600 combine where we just replaced the 28 tooth chain sprocket on the intermediate cylinder. once we got everything put back together, fired it up, and engaged the rear part of the machine, we've been having the outermost of the 3 cylinder drive belts jump off it's track to dangle loose while the other 2 jump over 1 slot to the right on the large cylinder drive pulley (they stay in the same spot on the smaller cylinder drive sheave). when i loosened the tension on them to put them back on in their right spots, i noticed when i was putting the tension back on that the outer belt got the tightest the quickest, with the middle one looser and the inner one the loosest. When we fired it up again they jumped again, so here i am asking if you all have dealt with this or might have any idea what's causing it. thanks and have a good one