Hey all. Fontana 90 converted to electric with 120 size motor and HV servos ball links on both side of control rods so tight with no play, straight level flight or vertical at any speed it’s smooth and quite but in a hover/torque roll as soon as I add enough throttle to hold or pull out a vibration which sure sounds like a flutter appears until moving again then goes away. Was worse with higher pitch prop. Prop is also balanced and tight with cotter pin hinges on all surfaces, sealed gaps. I’ve setup around 10 airframes before with out this problem and enjoy the setup dial in airframe process. Any thoughts on my hover noise?