Hi,
I bought a house that came with a Dimension One (Sahara) two-pump hot tub. Nice unit, and it seemed to work when we looked at the house, but the water was out when we got the house. Filled it and got a 'low flow - change filters or check water level' message.
Determined that although the circulation pump (Laing sm-909-nhw-26 3/4") was getting a full 120V from the control board, it was not spinning. Occasionally I could hear it spin, but only for a few seconds.
Took the pump off and apart, and the rotor looks like it had been dragging on the housing - not the impeller, the actual magnetic rotor. The magnets seem a little weak, but I have nothing to compare them to. New pump$ are available at a $ignificant price. Before I head to the parts store, is there anything else I can check?
Oh, and if I bypass the pressure switch, the control panel says it is starting to heat.. but then the thermal switch cuts off the heater, because there is no water flow.
Resistance of the pump is about 44 ohms from white to black, and twice that from white to blue. That seems about right too.

Your Lanig pump needs to be replaced, we have them on the our website. Yes they are a pricey pump, but if maintained well they will last a long time.