I have a vita spa hot tub model ptaxld15-rong. 120v 15 amp 60Hz. We bought it used and the only time we have a problem with it is when we disconnect the power either for cleaning or power outages. When we plug it back the pump doesn't start circulating water right away we need to unplug it and plug it back in a few times before it will start working properly once it is working it runs fine till the next time we power it down. This last time the power went out and we tried to power it back on I hear a humming noise like it wants to start but wont. Any thoughts?