I've had my welder for some years now and it's done a lot of work. I switched it on today and noticed a click when plugging into the mains as if a solenoid had been energised. Then I switched on the welder at its switch and attempted to use it. It was then I noticed gas was already coming out the nozzle. Then touched the wire to the earthed metal work and it arced without touching the trigger. Has anyone any ideas what it could be?