Theory:
Too much anti-sieze is added to a bearing that is bathed in oil. What happens to the oil? The machine in question had "metals" in the oil samples, high axial vibrations and the oil viscosity was reduced from 150 to 50. I believe the bearing heated up and froze as to prevent...
What's your history like? Did you experience any restart issues after a recent maintenance job? I would stop looking at the motors (my I&E guys would flog me but..)and start looking at the power source(s). If you are in an area that was effected by the black-out, perhaps it effected the control...
