Tell us more, I want to know all the details, how did you get it plated!?
The plating was done by a local electroplater. He did the both the gold and zinc plating.
The basic steps for restoring are;
Photograph before tear down and during every step
Clean the worst of the grime off
Document which wires go to what
De-solder and trim wiring but make sure you leave them as long as possible
Remove the screws from the gearbox
Gently remove the cover to expose the nylon gear
Remove nylon gear assembly
Unscrew the motor from the gearbox (the brushes will spring out when removed from comutator)
Cut wire from brush assembly
Undo slotted screws in the center of the motor base
Remove armature and field windings as a unit. The field will more than likely be stuck to the housing so extreme caution and patients is required while removing.
Inspect windings and armature and them blow down with compressed air
Degrease and clean all parts. Glass bead the gearbox to remove the worst of the corrosion. Then use wire wool and Mothers polish to restore the finish
Send out motor housing and screws for re-plating
Replace main wire that goes between the brush assembly and the solder connection on gearbox
Replace sleeving on all exposed wiring
When parts come back from replaters, reassemble.
Make sure to put fresh grease in the gearbox
Test using the test procedure in the FSM
Good luck and enjoy