I have a replacement B&S engine that has managed to break two bushings that hold the blade to the crankshaft. What happened is that engine would start making a clanking noise, and the blade would fall off. I would discover that the bushing was broken and the flywheel key was sheared. Last August I decided to give it one last try. I replaced the bushing and flywheel key, and torqued down hard on the flywheel. It has run fine since then, probably a dozen times or so. My theory is that the flywheel must have come loose, causing the spark to fire at the wrong time and the engine to try to reverse. Would this be enough to break the bushing?