Number one and most important is rear feed chain strippers are needed for most conditions of corn. Also transition of crop from rear feed to cylinder can give you a problem. Things that can hurt the transition: Rock door has old 1"X1" rock bar installed on door, rock sump is installed with nothing installed to help support crop as it goes over sump, third helical from gearbox dumping crop back into flow at left side of chain. Things that will help prevent jumping: Install stripper for corn and it is preferable to remove for other crops, install hump kit onto rock door, if sump is installed then check with me and I'll get you lined up with a kit to help support crop as it flows over sump, extend third helical from gearbox over top left corner of feeder opening to reduce load on left side of chain, make sure concave clearance is close enough to such material away from feed chain. Also like the other guys said you may have to loosen slats to get chain back straight again and check it out that one side of chain isn't particalarly loose like chain has stretched way more on one side or the other.