Jo, One more trick thats worked for us is to loosen all the slat bolts slightly.Next pry the chain all the way to the other side of the drum.Pry the drum all the way to other side of its main shaft.Turn the chain through slowly to preload it the other way,now retighten the bolts.Sometimes the chain kinda gets sprung one way, this technique springs it back.The updated drum rings help keep the chain from jumping in the first place.Bad habits are hard to break. Good luck! Hyper