Thanks for the prompt responses, I think I may try the US option while I tap away making replacements by hand. A word of caution about using gasket compound on carburettors though; even the tiniest fragment of Hylomar detaching itself in the float chamber or elsewhere could block a jet and cause the engine to stop and not start again till stripped down and cleaned. I would stick to gaskets lightly smeared with grease, which is why I want new ones which can still be compressed to make a good seal. If you have defects big enough to require a gap filling compound then your carb is probably junk anyway.
It would be interesting to find out if the same carb is used on any other engines like lawn mowers or generators, which might provide an alternative source of parts. The Lister/Petter diesel in my mate's boat is the same as used on truck refrigeration units and you can order parts direct from the manufacturer. By the way, a full engine service for a new Beta diesel in a 40 footer cost less than the quoted £85.
