I've moved the thread where others can see it, and several folks here may be able to help you. However, I will offer a couple of comments.

1. Most of us here who've worked in service over the years have learned the hard way to NEVER assume that "it" (whatever "it" is) works probably, just because it's new.

2. Motors usually trip because of excess current OR excess heat. In practice, these two usually are related. BUT, it will help folks help you to know whether the motor is tripping internally, or whether the external breaker is tripping.

3. Also, ratings matter. If you would look on the motor label, you should be find some like FLA or FLRA or RA (full load amps or full load running amps or running amps). Finding that value would be relevant.

4. If you can get your hands on a clamp-on ammeter, and can place it over one of the 220V wires during motor start-up, you'll be able to see exactly what amps your motor pulls, both during startup and during operation.

5. If you can also check the VOLTS, during startup, that can help identify current supply problems, like undersized wiring to the motor.

6. Finally, contrary to what most people think, centrifugal pumps overload during minimum flow restriction, not during maximum restriction. In your case, if there's not enough resistance to airflow, it could overload both your old and your new pump. In that case, simply installing a valve in between the pump and the spa, and throttling the valve till the amps (on the ammeter mentioned above) are in range, could fix your problem.

Good luck!

Ben