There are many tools on the market to use in conjunction with lubrication – mechanic’s stethoscopes, “smart” grease guns which use ultrasonic, or just an ultrasonic tool itself. High-frequency vibration measurements can also do this.
Most industrial maintenance mechanics who are involved with precision shaft alignment are familiar with the phenomenon of soft foot. Alignment standpoint, soft foot causes: Changes in alignment values, between when the hold down bolts are loose, and when they are tight. Non-repeatability in alignment measurements, especially if the bolts are not tightened in the same order and manner each time.