Suffolk Punch

Looking for spares for zenith carburetter, at least i think it a zenith please correct me i will attach a photo of carb.

My problem is petrol leaking from the overflow hole when you use the tickler which it should but it continues to dribble out. 

What i gather from the leak i think it might be the float not sealing on the needle valve which should stop the overflow.

Looking for advice and is it still possible to get spares or is that pie in the sky??