Combines ROTOR OUT OF BAlANCEIJ

PHE; Maybe the rock took a bar or two off the rotor, or there is a ton of dust behind the bar supports, and_or a hole in the rotor skin that lets dirt in and then the dirt settles and stays in one spot inside the rotor when the seperator is engaged. It hadn't ought to shimmy that much. As for elephant ears, they should have good squared edges that aren't worn to a bevel. look at the seive action when it's running too. Shot parts there will cause vibes as well.

Does the machine have a chopperIJ If so that could the the culprit of shaking if one of the spinning knives on it has a piece missing or if it is just broke. That can really make the combine shake as well.

I would consider looking for different combine. Sounds like this old boy had a rough home. OR tell them to call me back when they have solved and fixed the vibration problem because this old boy has a serious vibration problem.

To determine if vibration is from the rotor, try operating the separator with the rotor shifted out of gear.

Drop the one belt on the upper right hand side that drives the fan jackshaft, and kick the Rotor in gear and get it up to 900Rpm or so and it will be the only thing running. This eliminates shoe, fan, beater, and bedding augers. Just tell them you heard you could do this when you have a draper header. You just want to see it for yourself, perfect excuse for the (Red) beginner.