Re: symptomes of gummed up carbs
Carb rebuild is indicated by the leak - kit will include the inlet needle valve, valve seat, gaskets, o-rings.
Disassemble, clean, reassemble is pretty basic. take 'em apart, soak 'em in carb cleaner, put 'em back together. Sorry I can't speak to removal & reinstall on your inboard engine - outboards are pretty straightforward.
any case I wouldn't attempt it without a repair manual.
video tutuorial from themarinedoctor.com