Thanks for starting this off.
Pilot injector seems ok - good steady flame. If the pilot thermocouple wasn't getting to temperature then the pilot would go out - correct? but it stays lit ok. It's just the main burner only staying lit for a few seconds that's foxing me.
There is no air...
I have a very old but well maintained Glow worm back boiler that I need to nurse through one last winter (I think it knows!) On firing up this weekend for the first time since March, the boiler lit - stayed lit for 30 seconds/minute then the gas valve shut everything off - even the pilot.
I...