Hi Peter,
I have just seen this thread and I have the same fridge in my MH. The only issue I have had with working on gas is that you need to turn the temperature knob up to max on initial lighting and then turn down to the desired temperature when the red pointer is fully in the green segment of the indicator. If the temperature is not set to max then it goes out.
You may have tried this but if you have then as you say it must be the thermocouple or gas valve at fault.
