I joined this forum today. I need help diagnosing a problem with my carburetor. It will only stay running with the choke all the way out, not like black smoke coming out of the tail pipe. It runs smooth with the choke out. When I push the choke in, it will die or the governor will surge a little bit and die unless I pull the choke all the way back out again. I have a 1939 9N model which I just purchased a week ago. Any ideas?