Small Engines (Lawn Mowers, etc.): Craftsman mower, crankcase breather, new spark

Question
It starts with ease, first pull... then stalls.  Oil was changed by turning mower upside down, then overfilled with oil.

Drained oil via the drain plug under the deck and let it drain for two days, refilled to correct level. Installed new spark plug and air cleaner.  I figure its the crankcase breather. It's under the flywheel though.
What else can I check before I pull the flywheel.
If I must pull the flywheel how do I inspect the breather.  It appears to be a large black rubber insert on the top of the crankcase.  

Answer
It ain't the breather John.

Sounds like a candidate for a carb clean to me.  Have you replaced the plug again.  Often when a mower is overfilled with oil it runs a bit and fouls the plug.  Take it out and take a look.  If the plug is oily that probably is your problem.  If the plug is dry, clean the carb.