My hot tub pump won't start. It's not ceased. Could it be a faulty overload switch?

I bought a used 115v single speed spa/pool pump to replace the one on my hot tub. It was tested and certified as working and worked when I tested it. Several months later I'm getting around to installing it and finding that it won't start. It's not ceased as I can easily turn the impeller. There is 115v power to the terminals. Could this be a faulty overload switch or some other device. I don't have it installed in the hot tub (not flooded) just sitting beside it hooked up to the 115v supply and with the heater turned off.