Per my factory rep, you may have an under-powered motor, or the motor is too small.

You should look at the amp rating on the motor plate and put an amp probe on the motor when it starts bogging down. The unit is likely starved for power, a weak ground, low voltage, poor connection, burnt contacts on starter or pressure switch etc…Amp probe will most likely show over-amping. Under size wire from panel. Too long of a run on wire itself from panel.

If you don't have one you can always have an electrician or motor repair rep take a look at it.

BTW, the RPM on the pump is good, with the motor Pulley size you have and the pump Flywheel, your pump is spinning at 533 rpm, which is ideal.

- MTR

Glad to help!

As for the Valve Kit installation:

They are really easy to screw up, honestly. The retainers and the seats both screw in.

Retainer, spring, disc, brass seat. Or, Brass seat, disc, spring, Retainer.

If a single valve goes in wrong, it can damage the pump.

Make sure to install the valves one at a time.

For a diagram, you can click on the below link, which should help:

www.mastertoolrepair.com/kellogg-parts-321-pump-p-5411.html

- MTR