You're getting lots of good stuff from these guys. Let me throw in another thought about the flybar. There are 3 things that I know will cause TBE. 1-Absolute freedom of movement of the flybar is critical. 2- bent shafts will cause problems. 3- blade balance will cause it. You've covered 2 and 3, so look at #1 again.
First, is the rotor / flybar linkage binding? You should be able to wiggle the link on the balls. Is the link sticky? Many of the new blades have just a bit of flash on the link balls on the blades. If you have the slightest plastic flash, scrape it off with a knife. Or use very fine sandpaper. DON'T rough up the surface of the balls. When you flick one end of the flybar, it should bounce back and forth before coming to rest.
Hmmm, Remove the link from the upper blade and ensure the flybar is free.
Check the shafts by moving your throttle stick fully right, then apply a little power and look at the hub from the top. Then move the throttle stick fully left and apply a little power. How does that top hub look when viewed from above? Oh, this test works best with the blades removed.
I had one of the plastic bearing holders go bad. It didn't stay seated square on the top of the outer shaft. A replacement with the aluminum bearing cup and new bearings fixed it.

Does the heli shake if you hold it in your hand and run up the RPM? If it shakes, it may be knocking the flybar out of balance as it spins, yet it will look fine when it stops.
Maybe something in here helps. Hope so.
Good luck
Soloboss