My Ryobi 524 doubles

I run a 524. I am having a doubling problem between 2nd and 3rd units. It is a very consistent vertical doubling. From gripper to tail all the way across. Up then down every sheet any weight of stock. Any help out there? thank you

 

I would check the gripper pads first, then the gripper shaft that holds the pads.It seems if the pads are slightly worn on these it tends to double the length of the sheet.make sure they are in adjustment and the pads are not worn out. That would be the starting point.

 

Every second sheet is impression cyl grippers or cam follower, every third sheet is transfer drum, Can be a job to set, If in doubt get a techie in.