Drain the gas, download a manual, take the carb apart and clean it really well with carb cleaner and blow compressed air through all the jets and openings. After that long sitting its probably gunked up. If you don’t have a compressor a cheap can of keyboard spray works. May as well replace the plug to. Get a battery charger and multi meter to check it with. Only put ethanol free back in it. Do this with your son its a great experience. I’ve rebuilt a couple thing with mine and we both have learned a lot. I would think it will crank right up after that given your not having to figure out what someone else did to it. Looks brand new! (edited)