Which method is least effective for troubleshooting electrical motor issues?

Ignoring vibrations is least effective for troubleshooting electrical motor issues because vibrations are often early indicators of underlying problems such as misalignment, imbalance, or mechanical wear. Vibration analysis can provide critical insights into the health of the motor and its components, making it a valuable tool for identifying potential issues before they escalate.

In contrast, visual inspection can reveal obvious signs of wear or damage, using diagnostic equipment allows for more precise measurements and assessments, and consulting electrical schematics can help understand the motor's wiring and operational parameters. By disregarding vibrations, a significant diagnostic avenue is lost, which could lead to missed opportunities for preventive maintenance or timely repairs.