Sample repair job done recently:  (This was an on- aircraft repair- not a component overhaul).  Alternator Repair on Cessna 152 - Ford 60 Amp 10300  belt driven. In- flight, aircraft commander observed low-voltage warning light illuminated on instrument panel. On the ground, checked charging system. 28V at Field terminal but no discernible magnetic field in vicinity of Rotor.  Alternator removed from aircraft and spare, known to be serviceable alternator fitted. All satisfactory. Stripped unserviceable alternator and found that part of plastic brush holder had broken off, allowing brushes to disintegrate which explained no alternator output due to no Rotor magnetic field! Fitted new brush holder and replaced rectifier mounting bolts/screws which had sheared off due to corrosion while removing the output connections. Fitted new bearings, brushes, terminal nuts etc. Checked rectifier diodes for correct bias  etc. Ran up alternator in workshop and verified output current & voltage. Wire-locked frame socket head screws post test. Re-fitted to aircraft, all satisfactory.

Alternator dis-assembled

New parts - bearings etc

Heating end frame before pressing in new bearing.

Installing new bearing using Arbor Press

New bearing fitted. Bearing retainer - 3 No 2BA screws.

Hole in brush-holder allows a piece of lock-wire to keep brush springs compressed while re-assembling alternator. Wire is removed post assembly.

Iniitial Tightening ofpulley nut

Reassembled - just remains to lock-wire frame socket head screws after running alternator and verifying output voltage and current.