Although mine is usable, it's over-rich and costing a fortune in fuel.
I suspect it's just sunk/badly adjusted floats, but with my luck if I try to do something with it, I'll end up with no carb at all.
I have a new one on order, but it's in the missing crate.
If someone has a spare, I can tinker with the one I have with the knowlege that a back-up is there if really needed.