I am no engineer however it appears. The way the cam tunnel is closed off from the top and open on the bottom there is a significant amount of movement that's taking place causing a crack in these thin areas.. the cracks were not visible to the eye until this go around.. however the motor would not hold cam bearings very well since day one.. which tells me they have always been there and probably open up with heat causing the bearings to lose their press.. this application is a 55 mm cam