ideal Classic ff380 intermittent main burner not firing

[tonyla]

the fan starts up, the pilot lights up, but occasionally the main burner fails to ignite. Turning the boiler off and waiting for a while seems to get it going again, but I suspect this is an intermittent fault which eventually will cause the boiler to fail permanently.
The fauklt finder chart suggests the main gas solenoid valve needs replacing, but I'm no expert, so any help gratefully received.

 

[gas4you]

Assuming the pilot is the correct size and position, it does sound like the gas valve.

I've only ever replaced the entire valve on these, not certain if a solenoid is available seperately.

Needs and RGI in to assess and repair. Gas valves on these can be a pig to change.