Like I said, I can’t be sure. However, having this happen to 2 router from 2 different places makes me heavy lean to there being something with one of the collets (or nuts). From having measured thousands of our collets I can say you get some crazy results with a badly ground collet (none of those make it to sale just to be clear).
A badly ground collet wouldn’t have even contact with the bore of the router. That could not only cause runout and vibration issues but differential stress. Under load all those would add up to additional issues possibly causing the damage seen here.
Or Chris is the most unlucky router buyer ever…
John Torrez
Think & Tinker / PreciseBits