I acquired a 3 week old "Yard King" self propelled lawnmower with a Briggs 5.5hp Quantum engine from a neighbor. She said she just bought it and hit a tree stump and it started vibrating. I put it on its side and can definatley see a slight wobble. It starts and runs with a slight vibration, and tends to want to slide to the right when I'm holding it still on concrete. Is it possible to "fix" the crankshaft? How hard is it to get the crank out on these engines? Is it worth it? I beleive a new crank is about $50.00. Any thoughts?