Small Engines (Lawn Mowers, etc.): gas in the oil, murray riding lawnmower, fuel line

Question
My father-in-laws Murray riding lawnmower with a 14 horse engine (one spark plug) has fuel in the oil and when you try to crank the motor, it acts as if it locked up. I have removed the spark plug and turned the motor over and it spits out fuel and oil. I have opened the carb and cleaned it out with carb cleaner and it didn't help. I even replaced the carb from another old unit he keeps for parts and no help. Is there a gasket that has gone bad or is this still a carb issue? Also, on the bottom of the carb bowl is a switch like unit with two wires to it. Could this be an issue. Any help would be appreciated.

Rick

Answer
Definitely a carb problem.
Clean the "original" carb and be sure to change the needle and seat. It will cost about 6.00. Splurge and replace the gaskets while you are there.
Most carb cleans fail because of the steps you skipped which caused the problem to begin with. Whatever caused the problem is still there.
Clean the tank, and replace the fuel line and filter. You must be white glove clean about this repair.