Small Engines (Lawn Mowers, etc.): Craftsman self propelled runs rough, craftsman 917, cinder block

Question
I hit a small stump with my craftsman 917.376.582 and the engine abruptly stopped. When I restarted it, a loud wrapping sound accompanied the sound of the motor. I removed the flywheel and the key was in perfect shape. Then I took the blade off and restarted it, it sounded like the wrapping stopped but the lack of a load made the engine surge. I checked the crankshaft (adapter) with a makeshift dial indicator (pry bar on a cinder block) and its not 100% true but its not off by much either. I then replaced the blade with a new one and the engine surge was gone but the wrapping was back. I'm lost at this point and alcan only guess its the adapter or the crank.

Answer
Are the engine mounts tight?  Did you torque the flywheel?  Did you torque the blade bolt?  Did you scrub the blade adapter clean with soap, water and a brush to make certain it is not cracked?

Is the blade hitting the deck?  

If you have the Briggs engine 125K02-0500-E1 then I doubt there is any internal damage as these engines are pretty durable.  If the engine starts easy and runs fine then I would suspect the noise to be external of the engine.

Re-check the bolts to make sure they are tight and make sure the blade is not hitting the deck.

Eric