Bcchi,
Yeah, the plug cap not being seated was the first thing I thought of too, had that problem before. There's a possibility that it's not all the way seated but when I push it on, it goes all the way until the plug cap bottoms out against the cylinder head, then springs back about 1/8" so there's a gap between the head and the edge of the cap and part of the hex is showing. On all my other engines the hex is fully hidden by the cap but there's no way to push it on further since it's bottoming out on the head. On this one, there's no definitive "snap" when the cap seats like on my other engines. I'll try pushing it on with the spark plug out of the engine and see if goes further. If that's the problem, don't know what I can to to fix it. Tried it with the spring in and with it removed.
I agree, it sure seems like a spark problem. I took the carb apart and can't see anything wrong there. Nothing obviously wrong with the Hall sensor. Could just be a bad ignition box.
Scott