Mark....
Yes it was the rear cylinder that was not firing when the engine heated up ( that's what I meant by hot). Then eventually couldn't get it started at all....even on a good push start
It's not the case that one cylinder was running hotter
Initially I had replaced the black pick up with a new one ....also used a friends 3.5 stator and rotor to eliminate that as a problem.
I am going to order the Tritsch transducers and put the diode in series as advised.
Thanks again to everyone who took the time to share their knowledge with me