Just a minute Chris. There are not many Husqvarnas around here compared to Stihls but the burned/melted cases on the 350 family from loose mufflers are more seen than Stihl melts. Mike
Cool, a reply that's more than "But it's a Stihl!"
You're right, there are other design/manufacturing errors resulting in melted plastic - I'm not sure what the problem with the Husky mufflers was, although it may be improper hardware allowing the bolts to come lose, or like the muffler deflector on my Poulan 2775 that fatigue failed from vibration and melted the chain break. And that part will fail on every Type 1 2775, because it's a design error - but later versions fixed it and it's not repeated on every plastic Poulan.
I was specifically talking about the cases melting from the inboard clutch getting hot, which I don't see come up here other than on these plastic Stihls. Poulan actually did that on one saw too, the newer strato PP4218 - I don't have one and don't know why they don't show up here with melted cases.
I suspect the guy who owns the saw from the OP did just what my dad did - he wanted a good saw so he spent the extra money to get a Stihl MS250. What he got was a plastic clamshell pretty much like the plastic clamshells from everyone else. There are pluses and minuses of every design, but these are all similar and made of similar materials and construction techniques. The Stihls have an obvious weakness in that the clutch, which can get very hot very fast, is up against a material that can melt very quickly. If he'd have bought a Poulan Pro 5020 he'd have saved some money and got a saw that would have been much less easily damaged by this common operator mistake.
I've had an MS250 all apart, and there isn't a damn thing about it worth a penny more than a plastic clam from anyone else.