Ohh deary me......same result.  Played probably 25-30 games all up this morning and then as the day warmed up, fault started re-appearing and then same thing, got to a point where it wouldn't boot up a game again.  When it is running, the machine and game itself runs fine. 

Could it be a dud transformer - if so, what is the best way to test it without zapping myself and what are the chances of finding a replacement?  To look at it, it looks pretty ordinary, the insulation between the bindings has opened right up.