This is my last guess at what may be wrong with the machine.  I am pretty much over it at the moment.

I thought about this the other day and then forgot all about it.  The jacks Open has a 25 micro farad capacitor in the backbox.  There is one wire coming from it that got the cogs turning, a black wire - when I had a look at the scematics, pretty much everything that isn't working is linked by a black wire.  Would a bad cap give these type of symptoms, i.e. heat sensitive to the point where even the warmer weather here today rendered the machine useless whereas it was fine this morning.

Also, edit to my post above, on occasions the 100's or the 1000's score relay will reset the machine, it seems to depend on which score was triggered at the time the machine died, typically though it the the 10's which is the predominant score feature on the machine.