I have a Lincoln ranger 305D i haven’t had it long got it second hand with around 700 hours on it, the machine has been fine until recently the digital amp/volt read out when idling was saying 55 amps and 70 volts but when you ark up was fine, now after 5 mins of running the amps drop right off and doesnt weld at all no matter where you turn the amp dial to!! I read this is a common fault possibly with a PC board anyone know roughly how much or where I could get it changed? Thanks