It would be a good idea to have the armature checked with a growler . The problem will usually be one of three things , cutout , armature or the field coils . If you can remove the cover on the cut out , the cut out points will be visible . The cut out is like a cut off switch . When the points close allows the generator to charge . If the points in the cutout won't open and close on their own the generator can't function normally . . If the points never open , the generator will try to motor when not in use and either kill the battery or burn out the generator . If the armature is magnetized the generator can't charge , this is where the growler tool comes in handy . Being as modern vehicles have used an alternator for the last forty or fifty years instead of the generator , most shops no longer need or use a growler . I usually need to replace the field coils more often than the armature in old generators that no longer charge . The brushes , brush holders and springs will often need replacement if obviously damaged . Without the use of a growler and continuity testing device , a person will have to depend on luck or guess work . If a person doesn't have the tools and experience with a three brush generator , I would suggest a rebuilt generator or find an electric shop that can rebuild generators .
I had to depend on guess work when I had generator problems . I finally got lucky when the GMC dealer retired and gave me the growler that he had used back in the days when vehicles still used generators .
