The V-shaped notch in the pitch change horn on your first picture looks a killer. God knows what stress that has induced in the metal. I wouldn't think blending out was a solution there!
As for the other marks how about a high altitude tail rotor stall through mishandling? I've done it on a Bell 206 at very high altitude when my foot slipped off the right peddle. Instant left peddle, lots of vibration but almost no yaw because the blades were stalled. ..might induce TR movement that you can't replicate on the ground? Just a thought.