What would be the reasons if a repulsion induction motor fail to start

What would be the reasons if a repulsion induction motor fail to start

1. No supply voltage
2. Low voltage
3. Excessive overload
4. The bearing linling may be stuck or ‘frozen’ to the shaft
5. Armature may be rubbing
6. Brush yoke may be incorrectly located
7. Brush spacing may be wrong