I would agree on over torque causing it to crack. I work with a lot of white pine, so knots are unavoidble (hence the change to the segmented knives). I suppose it could have failed. That is probably equally like as the one that broke is the one of the 36-38 cutters on that side of the head and this being the one I removed and reinstalled. Killing me that I don't have any screws on hand to get back to work. No one has torx plus screws on hand locally and the specs are just slightly better on the torx plus over the standard hex head. I'm not willing to take the chance with a substitute. So I will wait for them to arrive.