On one of our Ryan IV's, we are having a pain in the ars problem as the chain is jumping off after about 7-10 minutes of operation. My question is: how much slack should be in the chain? The idler sprocket is moved as far forward as possible and still there is about 3/4 to and inch of play. The other units have about the same amount of play but no problems. 'Anyone ever experienced this? I could take a link out but it seems it would be way too tight. Would replacing the chain help???? I'm at my wits end. Help needed as rain is about to end I need this unit in the field.