I have been using a Hede Nielsen Mig welder on and off for about twenty years. Suddenly it has started burning holes through 1.0/1.2 mm steel sheet when on its lowest setting. The arc looks and sounds more fierce than it used to. Any suggestions as to what has changed? Everything inside looks and feels ok (connections, switches etc) It has three large capacitors. Could one or more of these failing cause this? All suggestions welcome as I either need to fix it or buy a new welder.