I need help with a Miller Syncrowave 300 serial #JD731827. There's two problems I can see, one, the unit has a volt and amp meter and when the unit is switched on the volt meter reads about 50 volts. Problem two, when the high frequency switch is put in start or continuous from off the voltage drops to 40 and the spark gaps arc continuously. I talked to a locale tech about the problem and he suggested replacing the voltage sensor part #626-0251 and that hasn't fixed the problem. Anyone with suggestions please help...