[Al Skierkiewicz]

Although used motors will have worn brushes, generally the brush will take on a wear pattern that gives it better contact with the commutator. If the motor was thermally stressed in the past, the lubricant may have become sticky and is producing significant drag on the shaft ends. If the motors were stored in contact with each other or have had some rough handling during it's life, then it is possible that the magnets have a reduced field. I have been forced to replace pancake DC motors that have lost magnetic strength from video tape recorders in the past.