If it has a JAP 5 engine the usual carburettor was a Zenith 24T-2. This was also fitted to the petrol versions of the grey Ferguson T-20 series of tractors so any of the professional tractor parts suppliers should be able to supply a new carb. Try Agriline, they are usually pretty good.
You will need to change the jets over though- unless somebody’s been heavy handed with your existing jets you should be able to remove them and put them in the new carburettor body; otherwise Agriline do a relatively inexpensive repair kit for the 24T-2.
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