1968 9.5 HP Sportwin

[mjpol2000]

I have a 1968 9.5 Sportwin (9822D) and after I use it for a few days, it is impossible to start. The first couple of days, it starts on one pull and runs all day. I have checked the fuel, the idle speed, the mixture, plugs, etc. Anyone have any ideas?

[boats.net]

Check for spark at spark plug when fails to start.