Mark, I don't recall whether that Amal had adjustable jet centering like SU carburetors do. If it does, please follow the process carefully. I'm not sure I've ever owned a car with an SU carburetor that did not need a new needle and jet when I bought the car, due to amateurs not centering the jet properly. If the jet is properly centered and nobody has bent the needle, neither jet nor the needle should ever need replacement: they don't touch each other. Once they make contact however, the jet wears off-center and the mixture adjustment process does not work properly.
Nice work on the mower. It looks at least as good as new in the pictures.
