Having trouble with my Stec 55x Autopilot in my J. Havent done any trouble shooting but all ideas are considered helpful. When in nav gpss mode or nav alone it doesnt follow my Gps flight plan anymore. It just wonders off on its own and also when I select Hdg it doesnt follow my bug either. In Alt and Vs mode it works but thats it. On start up the internal check shows no faults but it might be checking the control face itself and not the servos or maybe its just a electrical check to everything. Any ideas? Hoping my roll servo is not the fault..