Plug cap is on. I took the CF rudder arm off the servo and put on a stock plastic one and the servo gittered, all while the engine was running. I will check that the wires are not rubbing, but when I took the arm off I thought I was eliminating that problem. I moved the aerial from its original position from down and out the bottom of the fuselage as I thought it was rubbing on the CF tail wheel. It now comes out the fuselage and attached to the top of the rudder. again not touching any other wires.