Try this

Here is a link that might be useful: Lebowski's vid

Looks like a 'Pulsa-Jet' carb. I thought I saw fuel dripping out on top of the tank in front, on the red thing. Possibly needs a diaphragm or maybe just tighten the screws holding the carb to the tank. The diaphragm is the fuel pump with this carb. The intake pulse draws up a shot of fuel and a spring returns the little dome into shape for the next pull. Also these have an automatic choke consisting of a spring-loaded round plate under the air cleaner. If that is not opening properly, either because of binding or inadequate air flow, the mixture will be rich. This is okay until the engine warms up a little, then it will run rich. This choke is not the type that opens and then stays open - its for starting enrichment and it will close whenever air flow is not strong enough to keep it open. In this way, it also enriches the mixture for emergency power when you hit thick grass which slows the engine, but as soon as the engine speeds up it should open.
Check air filter element for cleanliness as well as hardening from age/old oil.
Typically, a failed diaphragm results in a lean condition or a no-start rather than a rich condition, but I don't believe your problem is linked to the governor system. I would check out the choke first. It should be only slightly open with the engine off and should open more after it starts. You can start it with the air cleaner assembly off to observe operation. This might also let you see where the fuel is coming from. You might want to have a fire extinguisher with you at that time. :) If the choke is not opening properly, you can use a probe to push it open and see if the engine runs better. It must be very free to move and will usually show a vibration when the engine is running.