Generally it's better to remove the carburetor from the engine to give it a thorough cleaning. As far as the needle goes, if there is any doubt about it just replace it. If you're having to pull the carburetor to clean it, I recommend you get a carburetor rebuild kit and change out the needle and seat (in the kit) as well as the carb gaskets and such anyway.
You can go
with the engine model number to find any engine parts or use the tractor model number for tractor parts. If the engine model does not come up with any parts images just let me know what the model and spec number is from the engine (or get me the tractor model number) and I'll find the part number for the kit and anything else you may need.
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