Just spent the last hour trying to find the vibration on mine. Removed the blades and ran it up with just the flybar paddles on. Had a little vibration, so I loosened the wheel collars and slid the bar over and then rechecked. No vibration. Balanced the blades, then installed them. Still a little vibration in idle up mode. Very little in normal mode. Added some tape to one blade, tried it, then removed and added to the other blade. Nothing will get rid of that small amount of vibration. I have a brand new main shaft in it, and it hasn't been crashed since the install. I'll just let it go for now. ??? Don't know where it's at and what's causing it!