That's kind of what I was getting at. The electronics on these engines are capable of self correcting for an imbalance and often don't show up enough with a cutout test. This is the hardest thing we look for today because we rely on the electronics too much. I like your "vibration" test to find some idea of where to start from. I just happen to be lucky enough to be able to go further, and thought maybe I would add some extra that might help. I truly feel for your frustration at trying to find these problems.