i have been through the routine recently . Seems The tensioner is a very weak point in the 103 engine. They go bad on their own, not due to lack of maintainance. simply replace it and all will be normal ,with my unit a slipping /jerky belt caused the alternator to break the carbon bushes too. replaced the cut out. Normal charging now , no squeals.the telltale sign of a bad tensioner.
mak
300se