Thanks for the leads you two. When I collected the dripping fuel I noticed it had a slightly cloudy appearance, suggesting water contamination. Can the carburettor tolerate a certain amount of the unwanted H 2O? I just poured a drop of metho into the tank in the hope that will remove any traces.
The mower, whilst undercover, has been splashed with water a couple of times due to overflowing blocked guttering during heavy sustained downpours and it seems the vented fuel caps allow water ingress into the tank if enough drips over them.
