I presume you've checked the brushes and that they're not sticking in their holders. Have you got power across the brush holders? If yes then you will have to check the armature. Remove the brushes and place the probes of your multi meter (on low Ohms range) across 2 segments. Mark the first with a pencil to remind you where you started. Go round the commutator checking each pair of segments as you go. All readings should be about the same. If you don't have power across the brush holders then the problem can only bee in the wiring or a faulty component (check even new ones). Don't forget the switch.
Norbert, October 2012
