HiI have a hirobo shuttle plus. Gyro Futaba 401. Servo rudder, align DS620 with voltage reducer to 5.1v.My problem is the servo rudder vibrates when the engine turn on. If the engine is not turn on, then there is no vibration.I have the same issue previously with my trex600. However it was resolved by just moving the gyro position. Same gyro and same servo rudder.When I say it's vibrating, the servo just keep moving from left to right and vice versa (very small movement, about 2mm). No problem during flight as the head lock still lock, however after 5 minute flight, the servo rudder become extremely hot.Any one has the same experience before that they can share?ThanksEric