I would check to make sure everything is moving freely. I had problems with my MicroHeli CNC rotor head binding...light silicone grease fixed it nicely. Check to make sure you are not topping or bottoming out on the collective controls. Unplug your motor and check to see if you are binding perhaps...also check your servos...I had a problem with the stock servos not moving together in unison(sp?) I could fix that with my radio...but you can't do that with the stock radio...