rear bearing failure

The eaton m90 rear bearings let go and totaly recked the charger .This is a custom fit to a straight six supra.I am using a manual tensioner from the doner xjr6 jaguar and havnt chewd any belts yet.I have been reading that the tensioner failing can cause the rear needle bearings to let go.Has anybody had this happen before.I can only presume that the bearing in the tensioner seizes and puts too much strain on the charger,which in turn puts too much starin on the rear bearings.
I have rebuilt another eaton m90 now and dont want to reck this one due to overlooking a problem that could still be with me.