Hey Lou
Lou, remember me? We emailed when you first found this site. I haven't been here in a long time and man-o-man, things have changed!!
With respect to your alternator problem, my first suspicion would be TOO much belt tension. It would heat up the alternator bearings causing them to bind. Then, it would be a self-perpetuating cycle that could fatigue the idler and mounting bolts and explain the rest of things you describe.
I've never really studied the 280 alternator system, but that would be my first guess after reading your description. Does the 280 use a flat, "V", or syncronous (toothed flat) belt? Is the tensioner spring-loaded or fixed position? If it's spring loaded, was there spring travel left when the belt was at tension?
Does the alternator shaft turn freely without the belt?
Food for thought.....
Chris