What is the histoty of the saw? Did you get it used? If the previous owner did not maintain it properly then you can chalk this one up to experience. Scoring would be a real bad situation. Did you check the compression? Its too bad because the ms440 is one of the best saws out there. The good news is that Stihl has the highest resale value from any brand. If you put it on ebay and get good money for that can go toward a new saw (perhaps another ms440?)

I bought the saw new. After I had used it a few times I noticed dust in the carb throat, so I took it back to the dealer. He checked the filter plate, the filter and said he couldn't find anything. I had taken the carb off to clean it, and noticed someone had clipped the rubber tube that connects the filter plate to carb. That is where the dust was coming from. The saw doesn't have many hours on it, but is old enough the warranty is out. Could that dust cause the damage that quickly?
Brett