You want to double check the wire connections in the pump housing. It appears you are getting power to the pump so maybe it could be just a loose connection on one of terminals.
The below is something I copied from an earlier post regarding a pool pump. I cannot attain to is accuracy or if applicable to your booster motor but logically it is a good process to review if you inclined to.
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With the meter set to Volts AC measure the pump input between L1 and L2.. If you have about 240 VAC, then the pump should be running, so the pump has to be bad.. If you don't have 240 VAC, that is why the pump is not running.. Keep in mind that you must measure between L1 and L2.. You can't measure between L1 and ground and L2 and ground as this can give you an incorrect reading..
If no voltage is getting to the pump, you need to follow the circuit back to what tells the pump to run.. Most likely a relay called the Pump/Filter relay. Measure the output of the relay, between the two output pins.. L1 and L2.. If you have 240 VAC there, then the wires between the relay and the pump have an issue.. If you have no voltage on the output of the relay, check the two input pins.. If you have voltage on the input pins but not on the output pins, then the relay is not being turned on, or the relay is bad..
If you have no voltage on the relay's input pins, then you need to follow the circuit back to whatever feeds the relay, most likely a circuit breaker.. Do the same thing again.. Measure the circuit breaker's output (between L1 and L2) and see what voltage you have. If you have no voltage out of the circuit breaker, then the breaker is popped, bad, or no power is being applied to the automation panel.
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