Rotor
1. Check the circuit between slip rings with an ohmmeter (1) rotor. If the circuit is open, replace the rotor.
2. Check the circuit between the slip rings (1) and rotor (2) or rotor shaft (3). If the circuit is shorted, replace the rotor.
Stator
3. Connect the stator winding leads in pairs (4) and check the continuity of the circuit. If the circuit is open, replace the stator.
4. Check for continuity between each winding terminal and the stator frame. If the circuit is short, replace the stator.