I had a Victa Vantage that did that.Was going great until I lent it out.After it came back I was mowing my lawns when all of a sudden it just stopped.I couldn't pull the cord it was like it had locked up.I waited until it cooled down.Then I could pull it again,but it just would not start.So I pulled the muffler off and looked inside.'Oh my' is what I sort of said.The rings were in-bedded into the piston.The scores in the bore were very deep.I don't know exactly what caused such a mess,but the engine was dead.I hope that hasn't happen to yours.
