I'm new here, hopefully you guys can help me out. I have a Sears Craftsman push mower w/bag that is 14 months old. It has 6 horsepower I believe, its just the basic lawn mower. Earlier this summer I hit a tree stump that was not recessed into the ground as deeply as I thought, since then the mower has given me problems. Upon startup it now blows out blue smoke (oil) and seems to rev much much slower then before. It vibrates and shakes. In order to ensure the blade was not hitting the deck I swapped the stock 21" for a 19". It has plenty of clearance but still vibrates/shakes and does not run well at all. There seems to be some play in the shaft holding the blade, maybe the crank is bent? I'm far from a mechanic so thats about as best as I can describe the trouble. What do you guys think? I do not have much property so a real basic mower would be fine. Am I better off just junking this one and getting a cheap one? Is this worth getting fixed?