Is it worth putting new brushes in an alternator that has never been replaced? Car's at 120,000 miles. What else is needed to rebuild an alternator? I know it's a lot cheaper than buying a new alternator.
Besides the brushes, the front and rear bearings should be replaced and the rotor and stator windings should be inspected visually and electrically with a ohmmeter. The regulator should be tested as well as the diodes. If the copper commutator bars are very worn on the rotor then just get a rebuilt unit because it will not be dependable even with all the other parts new.