On Thursday, August 4, 2016 at 12:32:51 PM UTC+1, wrote:
The gas valve and / or burner on my faithful old Sunrod G50 boiler have finally failed after about 50 years use.

Unlikely, I know, but I don't suppose anyone has these parts available, or any idea where I could get them?

I would really like to keep this extremely reliable boiler going if at all possible.

I'd appreciate any advice.

Many thanks,

John

Just to close this off, Andrew was quite correct. The combustion channels were totally blocked with soot. Once we cleaned this out the boiler worked perfectly. I shall make sure this is done every year from now on.
Many thanks for this valuable advice which hopefully resulted in many more years' service from this boiler.
John