Previous owner said it simply "stopped" and needed a new "card."
I used a Jewellers eyepiece to read the rating (3.3ohms and 7watts)and was ecstatic to find that the component was locally available for AUD1.80. A nice little saving.
I actually got a 10watt as it takes more heat. The repaired card (below) was whacked into the mig and now sweeps through its range and at all power settings.
Most of the smaller "hobby" migs are very similar inside. The resister is a different rating from make to make but the principals are the same.
Hope this helps somebody, in all I've got about an hours repair time in it and a couple of hours search time. Thanks to Lilly, my assistant