I am not about to debate oils, other manufacturers making "dud" models, heck I won't even mention the first run of MS 661's were shite.
What I see here is one guy wrecked two saws and to me that is not a basis of any particular model fault complaint.
Now if every, or every other, or even a certain batch number of 462's were showing identical problems- maybe......
Coincidence there has been a recent upgrade- maybe. Maybe release of details of the upgrade prompted the complaint?
What I will say, in agreement with a couple of previous posters- the M2 is cast inside the port for Stihl Techs to identify which model THEY are working on- read your owner manuals and warranty cards- we are not supposed to pull new model saws apart and work on them, Stihl are under no obligation to mark or stamp any saw they make or improve with alterations during a production run- apart from model, serial number and safety decals. They are not designed or marketed around any Joe with a garage and a T27 wrench to work on.