Vintage Horticultural and Garden Machinery Club

Glad to know you got a carb. I suspect it leaked a bit around bowl to body joint so owner thought tighten it more, hence the damage. There should be a gasket around top of float chamber.
The jet might be saved with a bit of careful ‘adjustment’ with pliers. The important part is the hole in the jet, not sure how critical the damaged part is, so long as it does not block the hole. I guess it could be there to ensure fuel is picked up when level drops in the float chamber.