It finally looks like the problem has been solved with the Jacks Open machine. Thanks to everyone that contributed and offered encouragment.
Turns out it was a power related contact on the AX relay that wasn't adjusted properly and was only just touching which would have been causing high resistance as the machine warmed up and then it got to a point where it just wouldn't work.
Anyway, played many many games on it yesterday and there were no signs of the machine faltering.
Thanks again.
