Kits with gasket, float, needle included are sold ebay ect.
Mmmm ... be aware Ebay is where the forgers sell, and some are even stamping "Amal" on jets and printing a similar-looking logo on packaging.
I always buy either direct from Burlen or at least from a reputable bricks-'n'-mortar dealer; you don't want to be chasing a problem and thinking you've eliminated a possible cause when you're fitting hookey parts ...
The horizontal tiny jet is a bad design prone to clogging with deposits..On the Amals with the non replaceable pilot jets.....I drill out the jet with something like a .025 drill, blow out the shavings and then screw in the proper sized pilot jet into the existing threaded hole in the top of the float chamber on the main body so it's like the early Concentric carbs.. The jets cost about $5 each and the best part is now you have a tunable low speed circuit and will never have to use a pokey tool to clean the jet....
With respect, the "bad design" was evolved when the original Concentric pilot jet location in the underside of the main body was found unsuitable for many 4-strokes. It then worked for years and years without any problem.
Afaict, it more became a problem - like many 'problems' with these old heaps - when they spent less time as their makers intended and more time as garage furniture, around the same time as the agri-businesses worked out there were huge profits to be made from persuading the politicians they could be seen to be Responding To Public Concern About The Environment (aka the media's version of the tree-huggers version of 'science')
by sanctioning the adulteration of vehicle fuel with ever-larger percentages of agri-businesses' products ...
If a non-replaceable pilot jet is being drilled out, fit a replaceable jet, which is even easier to access for inspection and any cleaning or tuning?