Locate the spa motor. In a portable spa it is located inside the cabinet, and with an in-ground spa, it is located away from the spa with the other equipment.
Make sure the power supply is connected properly. It is usually 110 or 220 volt. Typically the 110 volt will be a plug in, and a 230 volt application will be hard wired into a circuit breaker.
Check the power supply for the proper voltage with a volt meter. Do this carefully, to avoid shock. The tag attached to the motor will tell you the voltage required.
Check the power at the motor. There is a plate usually at one end of the motor, where the wires are connected from the power supply and the motor. This plate can be located by following the power supply cord to the motor.
Remove the cover. Inside this same area, there is a switch that turns on the motor when the on-and-off switch at the spa control panel is activated. Power can be checked at this point with a voltage meter. If the power supply checks out okay, the on-and-off switch may be bad, or the motor needs to be rebuilt or replaced.