I would use an volt/ohm meter to see if the alternator is working
set your meter to 25 volts DC put plus on red post and minus on
negative post on battery have someone start machine if needle or
read out don't go over 13 volts alternator is dead replace the diodes
or rectifiers same thing its lot cheaper than buying a new alternator
O'reillys auto parts has them don't know what they cost
willy