when I get a saw like this I can pull the muffler and tell whether its scored or not. if it is ,I go to the next step ,vac and pressure testing. so far every 562 that I have gotten in that was scored was an air leak. at that point I call husqvarna and get an authorization to fix or replace the saw. I have went so far as to send pics to Husqvarna of a bubbling seal or transfer cover and pics of the damage. then they make the call. if your dealer just pulls a muffler and says its toast and its your fault they are not much of a dealer.