you need a few degrees of right tail to hold it from the torque of the blades. if your unable to hold it with an input from the transmitter in the opposite direction of the way it's spinning then you either have the servo or the gyro reversed. a reversed gyro makes the tail spin uncontrollably, test it by holding the heli and yawing the tail in one direction and watch which way the servo moves, if you spin the heli to the right, the gyro should make the servo add left tail. you can get a HH gyro and replace the one you have but if the one you have works I'd recommend using it. if you just want a HH anyways, the Futaba GY-401 is hard to beat at the price.

kc