I hit a tree root in my front yard and bent the lawnmower blade, instead of replacing I bent blade back and continued to mow yard I hit another root. Lawnmower engine is now very loud and engine shaking enough to unscrew nut that holds air filter in place.any suggestions? I tried to take off blade before this happen but was not sure how to do it. Is there a chance the blade is un balance now or have I done something worst?