I bought a boat with a 1980 merc 200. This is my first boat or experiance with boats. The boat is difficult to start. Once I get it running it runs great, no stumbling or bogging. I usually start it by holding in the choke until it tries to start, and then release the choke and try to start it. Even then, sometimes it won't start. Is there another way I should try starting it? What else should I do?