Assuming you only get the vibration problem when the processor is engaged, the rotor is probably badly out of balance. If the machine was not turned over regularly during the off season, and _ or thoroughly cleaned inside of the rotor bar supports after last season, material lodged inside of the bar supports on the top of the rotor will drop off but material inside of the bottom bar supports will dry out and set hard leading to a badly out of balance rotor and a machine that gets an attack of severe shakes and almost skips around when the processor is engaged. If the problem occurs from start up then check all belt idlers and the main electric clutches for material lodged inside of the high speed idlers. A badly out of balance high speed idler can really shake a machine around. Maybe one day, AGCO will design a sloping plastic insert for the inner diameter of these idlers, that will slide dirt and dust out of the idler and prevent the build up that causes out of balance vibration.