1st you have a intermittent shutoff switch issues. 2nd most likely have a fouled primary fuel circuit . Aparently only the secondary priming circuit to the venturi is functioning .You will have to resolve both issues . Start with fresh fuel and 2 ounces of concentrated fuel conditioner within the fuel , let it sit over night . Start your unit and keep it running by depressing the primer bulb , keep running via primer and choke until it will run off choke ! Establish shut off switch continuity or replace defective switch !

Thanks for your reply. The switch has already been fixed; the wire going to the coil broke off at the switch; I soldered it back and now this works. For the fuel issue, you're saying that if I start it then keep pressing the primer bulb to keep it running, eventually it will clear itself?

All I did was pull the fuel line off the tank; was that a bad idea? What should I have done instead to stop the machine?

Yes Primer and Choke until fuel treatment loosens gumming within the fuel circuits . Normally with a manual choke , just turn choke on full to flood engine , it will stop . Otherwise wearing gloves pull off the plug wire much safer than fuel line on hot running engine .