Ernesto J. Wiedenbrug, Ph.D., SM IEEE Introduction Some squirrel-cage motors designed for high start-up torque may get weaker over time, needing longer startup times and may perhaps even trip during line-start – but never show big problems in vibration or MCSA. This paper explains what gives high startup torque motors their special capabilities, describes a common failure mode making it nearly impossible to find the issue using MCSA or vibration, and diagnostic alternatives for these problems.