I bet that hole got wallered out, I can barely see it in the pic but it looks egged. 

FYI, when you break the bolt, first thing you do is drop the horizontal auger chain off, fix the shear bolt and clean out the big auger.  Then put the bed auger chain back on and all is well.  That rice really packs in the big auger and is rough on the drive line. 

If you need some parts give me a call, I've got a 1480 parts machine at the barn with good unloading auger parts..