Combines 7720 problem

Make sure the fan isn't spinning on the shaft to some degree. Had this happen on a 9500 where the set screws can loose on a new combine. Can't remember if the 7720 had the same setup. The bad thing about this is the shaft sensor won't pick up the slower shaft speed because the shaft is turning. Couldn't figure why there was so much chaff in the tank.

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open your bottom sieve, your returning to much.

There is a roll pin on both the front and rear variable sheaves. It can only be checked bu taking the sheaves apart. If it is broken the sheaves will allow the belt to slip. Also there was a mod on the fan intake that required the opening in the side of the combine to be enlarged, you might want to check to see if yours has been done. However I think it is one of those roll pins. Good luck. If you have more questions you can e-mail me at chadnichol@hotmil.com

Your bottom sieve is closed to much,not letting