hello my friend
when assembling the motor was well the position of the magnet armature.
remember if the position not correct the magnet camps, a motor not move free, becouse the moviment is very strong. the magnet camps between the armature and the yoke make a good moviment. the points N,S. in the brackets have a point for correct assembly. the armature is inverse assembly. make an experience. retire the engine of the machine, connect the wire for battery and see the turn the engine, 15 minutes after verifier temperature and the sound.
see the marks in the yoke magnet or coil and brackets. see the wire in the armature isolation, and connection in the commutator, press with pointer, the wire in the commutator