Thanks @tottot for the possible explanation. That gives me something to work towards. I will try what you suggest and see if that helps, if not, I may try to clean up the carb with a refurb kit as it seems a relatively straightforward process...

I've acquired a Series 3 petrol, first registered in 1972 (K reg) - it's in generally pretty good condition and has had some money spent on it by previous owners. It's has a curious anomaly (as all old Land Rovers undoubtedly have!) in that the...