Hi Bikerhifinut,
Thanks for responding.
I followed your instructions and the first thing I found was that I had neglected to fit the LED resistor - R34. This immediately fixed my LED problem.
I proceeded to run the tests with the valves out as you described and I found the heater circuit to be correctly wired using a continuity test and I measure 6.5 volts on all the bases between 4/5 and 9 as expected.
However on fitting the valves I have exactly the same wrong readings in the heater circuit. You suggested this was indicative of a wiring error and I will check through the entire build again. In the meantime I will post some pictures in case there is anything standing out.
Regards, Graham