After your tail lets go, feel your servo.  My tail servo limits wereset too high and were allowing my servo to bind and go out.  I swappedout servos (the other one was toast) and gave it less total throw. It's been fine ever since.  Also, cheap servos (if that's what youhave) do terribly on the tail.  I've just started flying heli's, butthat's still what I've experienced.