Abstract: A probe guide assembly permits optical inspection of critical nuclear reactor coolant pump motor parts located inside a generally cylindrical motor housing without requiring disassembly of the motor. The assembly is removably mounted to the outside of the housing near a vent and includes a probe guide member for carrying an elongated probe guide that extends into the housing through the vent. The probe guide member is mounted to a cross bar that spans the vent in a first direction. The probe guide member can be moved to a selected position in the first direction along a slot in the cross bar and can rotate in the slot so as to angularly position an end of the probe guide interior the housing. The cross bar is adjustably positioned in a second direction across the vent by fastening the ends of the cross bar to different points along a pair of mounting bars extending in the second direction on opposite sides of the vent.