I have got a problem with the power valves only working some times. The valves are free when worked by hand so I do not think it is a de coke problem. I have done the test whereby you manually open the valves and turn on the ignition and they do not close so it seems to be electrical. When the ignition is on should there be power going to the servo motor and if so what colour wire? Any help with this problem would be greatly appreciated.