Glad you asked...
To rebuild electric motor you will need to first take the motor apart being sure not to lose any pieces. Replace all the brushes, clean all the interior parts and put the motor back together again. You can find more information here: http://www.ehow.com/how_4740040_rebuild-...
Then again, this answer might help you...
To rebuild an electric motor you will need solder, a soldering iron, x-acto knife, a Phillips screwdriver, a motor commutator lathe, a silver marker, new brushes and the electric motor that you want to rebuild.

