How do you know that the motor is overloaded? The first sign that a motor is the wrong size for the application is frequent nuisance tripping of the thermal reset (also called a thermal protector). Check to see if the applied voltage agrees with the nameplate. If it does, check to see if the motor and drive turn freely. If the voltage to the motor looks good, and the drive system has free motion, there may be a need to increase the horsepower of the motor. Check the power supply to make sure there is enough capability to go up one horsepower rating.
For situations where the motor's overload condition was extreme - possibly a frozen shaft - you'll see a start winding failure. This is when the motor never left the start winding and failed to come up to speed. The internal analysis will show the start winding to be discolored from extreme heat prior to its opening. The main winding will still be intact (Figure 3).