I brought a lawnmower in that was violently vibrating. When I arrived the mechanic/owner had a quick look and said the crank shaft, or an attachment to the crank shaft, is likely bent. He said he'd have a look, but if it was the crank shaft itself, that he wouldn't be able to fix it. When I picked up the lawnmower, he said that he couldn't fix it, so the lawnmower was essentially useless.... more