Rotor Check

Check the continuity between the slip rings of the field coil. If the resistance value is not within the standard value, replace the rotor.
Standard value: approximately 2 - 5 Ω

Fig 1: Checking Continuity Between Slip Rings Of Field Coil
Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
Check the continuity between the slip ring and the core. If there is continuity, replace the rotor.

Fig 2: Checking Continuity Between Slip Ring And Core
Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.