the motor is internally protected against overloads by an integral thermal protector. this is a thermal overload device that is embedded within the windings. stator laminations means how the iron punchings are arranged that make up the motor stator, this is what the windings are wound upon. the motor is of the induction type. its rotor is one piece made up of iron punchings laminated together with aluminum shorting bars on each end. locked rotor means the current that the motor is exposed to when the rotor is not turning as in frozen bearings. for troubleshooting a motor you'll need an analog meter and a clamp around ammeter. use the meter on its highest voltage adjustment and read the voltage on the line side of its contactor. when its running or trying to run use the ammeter around one conductor to direct read its current. compare that to its nameplate reading. the control circuit is probably 24 volt, so all the coils in the motor circuit will be running at 24 volts. there may be a control fuse on the secondary of the control transformer, this steps down the 120 volt to 24 volt for control.