I just got my RTF fully repaired and tested after coming in pretty hard on the tail. When I went to test it, it spooled up fine, no vibration, etc, but when I got light on the skids it just started to spin. I thought that I had ruined the gyro and started off in that direction. I was double checking everything even replaced the gyro with the gyro from my RxR. I was almost going to email HeliMax for help when I thought I should compare every mechanical setting to the RxR. DUH!! I realized that the RxR tail rotor rotates counter clockwise and my RTF was rotating CLOCKWISE. I think when I was replacing the tail boom, I got the belt twisted. Set it up for proper rotation and she flies FINE now. Considering how hard I hit, I think it held up pretty well! I'll continue hover practice with it but spend alot more time on the sim.