Illustrative integrated assessment
Assessment: Input-shaft bearing change is the leading hypothesis.
Evidence rationale: Vibration, IR thermography and ultrasonic monitoring provide local observations at GBX-2. Motor current provides drive-train evidence from the motor feeder without locating the gearbox bearing. Gearbox-sump oil provides system-level evidence without localizing the source. Speed, load and maintenance history qualify the comparison.
Next action: Verify lubrication delivery and repeat measurements at matched speed and load.
Field verification is required.