Probably the carb. Disassemble as far as you can take it down and clean well. Very well. I would install a kit for good measure. the kit because even if it gets perfectly clean, a diaphragm can become brittle with age and not pump the required amount of fuel, thus the full choke condition. Use fresh gas. Unless it's something else, which it can be, you should be fine. When cleaning, soaking, etc, if you don't have a compressor to blow through all the orifices, canned air will work.
