I have seen this happen to too many saws operated by novice owners, I will use my friend's case to show what I am talking about. He acquired a nice Homelite 47 and started using it without knowing anything about chainsaws or even having read anything about how to use them. Of course the chain quickly became dull and to make it keep cutting, he just kept putting more pressure on the bar, so much pressure that he was dragging the rpm down to the point where the clutch was slipping and often stalling the chain. The clutch got so hot it blistered the clutch cover and melted the chainbrake band into the plastic. No, he did not have the brake on, didn't know what it was for or how to use it. The needle bearing of the clutch had a plastic cage and the cage melted and stuck the clutch drum to the crankshaft. The smoke coming out of the saw didn't bother him too much, it's a 2-stroke engine and they all make smoke, right? The clutch now engages at such a low rpm that it's difficult to achieve a good idle. The clutch is a good three piece steel shoe unit with a wrap-around spring, is it possible that it got so hot, it softened the spring? This is the most extreme case of course, but I have seen a lot of blistered clutch covers.