I used the mig again yesterday for a 2-3 hours. It did infact suffer the same fate as before, the wire burning out.
The funny thing is though, it only did it the once an that was the very first pull of the trigger. It was fine after that, so it's definatly a lot better than it was ...
Im still a bit baffled as to why it did it even once though, had a multimeter on now an there's definatly no short anywhere, though I suppose there must be else it wouldn't even do it once.
I suppose intermittent faults are even harder to find aswell aren't they...