You know, what he is asking is not without precedent in US industry. I remember GM replacing the engines in some out of warranty Chevrolet Vegas back in the early 70's. Also, some car brands have repainted some makes whose paint jobs flaked off prematurely, though beyond warranty.
Sometimes there are class action lawsuits about a particular repeatedly defective model. I had a Dell Inspiron laptop whose power plug kept shorting out! There was a settlement in such a lawsuit. I had had the extended warranty, and twice during the warranty they sent a technician to replace the motherboard, as that was the only way to fix the thing where it would charge, but it wound tearing up again after the warranty ran out....
I am not an expert on such equipment. However, I fail to understand how it could be placed in storage on a shelf, intact, in a an environment that has some amount of protection from sun, humidity, and rain and then you pull it off and found the housing is cracked. That cracked, no matter what, had to have had some help, either routine or not-so-routine use.
If I were Stihl, I would document the complaint, the unit serial number, but not offer any replacement. If I were Stihl management and discovered complaints about other units of the same make and manufacture run were having the same trouble, I might reconsider. Who knows, they may find some type of pattern with quality control of the manufacturing materials or processed used on that model's particular run.
