The float just wouldn't rise up. So, removing it, I placed it in a bowl of water as it just had to be punctured. But it bobbed to the top and floated perfectly. My friend Hughie (with the D14/4) suggested removing the needle just in case that was faulty. So I did, and repeated the test again. Still the float stayed down! Putting my finger under it I felt a roughness when lifting it. Anyhow, I decided to replace it and sent off to Hitchcocks Motorcycles for some Amal spares...
You can find them at www.hitchcocksmotorcycles.com