One of the servo on my Aerobird Challenger keeps twitching. The arm is continuously moving up and down in a rapid, repeating motion. I have no idea what is causing this. I have not crashed recently. It just started one day. Do I have a bad servo of is the whole control board toast?

Mine will do that if there isn't enough tension on the tail horns. Try moving the elastic band to the bottom setting on the horn to increase the force on the wires,