My Neataheat 80e is not lighting up?

My Neataheat 80e began turnning itself on for about a minute then switching off and so on. I checked all the remote switching, e.g. programmer and room stat which were OK and set the stat to max and the programmer on constant and the same continued. Eventually it stopped coming on and off all together.

I suspect it may be the gas control valve, which I had to replace some two and a half years ago.