In my new to me house, I have a Gulf Coast 864 LEi hot tub (dated around 2008). It was "empty" when I bought the house and was closed when we moved in in december. Sure enough, the previous owner didn't drain it properly and water got in, froze and cracked one of the shutoff valves. Anyway, after fixing that, I filled it and turned it on, only to discover that one of the two jet pumps wasn't working. But the tub got up to temp and ran off the one pump ok. Circulation and little waterfall ran normally. Anyway, I finally got around to draining the tub and replacing the second pump (motor was frozen and previous owner had disconnected it). But now, after refilling and powering it up, the circulation pump isn't running. There is no sound from it. The other pumps work and the heater will come on but it quickly shuts off due to no flow. I checked for power in the circulation pump plug on the board and didn't get a reading so I wonder if there is some sort of sensor that is stopping the pump from running. Any ideas?
Control unit is a Balboa Equipment Pack VS510SZ w/4kW heater.