A little weeping is no big deal. Also, the spark doesn't look bright like a car or truch, IMO. I had a hard time seeing mine also, until I checked in the dark. More often then not, it has spark or no spark. Its not too often that its a weak spark, unless its a deal like that on a loose or bad ground. I'd say you are chasing a cylinder issue or carb problem. If the crank seal was bad, it would still run. I know this is basic, but does fuel poor freely from petcock? How bout when tipped over, does it come out of overflows? Exhaust is definately clear? U tried different throttle positions? Hows the kicker working? I have to get it just right on the sweet spot on top, so I get 2 cycles or it won't start. Especially right after the rings set-in and compression was the highest.
Air leaks or blown gaskets, will usually make it rev high.