The polaris booster pump motor does not start. I hear it humming. I took the end cap off and turned the shaft without a problem. I took off the capacitor and tested it and it works. What should I check next?

I think Polaris should refund the purchase price on these pumps. I changed the breaker, the whip, and upgraded the outlet (using 110). The dealer exchanged it for me, but would not give me a refund, and I had the same issue with the second motor. I used a Hayward 6060 pump as a replacement. Everything works fine.

on the end of the motor there is a plastic cap. Pop it off. This is the end of the shaft.On mine there is a slot for a flat head screw driver.You can break it loose with that.I gave mine a shot of WD-40

Usually when a polaris booster pump hums it means 1 of 2 things; either the starting capacitor needs to be replaced (its located under the black hump on top of the motor) or the pump is bad. Most likely the starting capacitor needs to be replaces. This is where you should start since the capcitor is only $20-$30. Get a new capacitor from a local pool store, shut the power off to the motor, remove two screws on each side of black hump on top of motor, remove two wires from starting capacitor and install wires on new capacitor, replace cover and turn the pump on. If that doesn't work you will need to replace the motor.

Pull the back cap off the motor and hold the shaft as you spin off the impeller. The rest is straight forward enough.

Lock the end of the shaft opposite the pump and then turn of the impeller counter clockwise looking at the pump. The remainder is simple nuts and bolts.

It is either the capacitor on the back of the motor or the windings of the motor. Motor capacitors.

Does it have a century motor? If so, remove the shaft cover plate at the rear and try rotating the shaft with a very thick slotted screwdriver or substitute until it turns fairly easily. Often some mild oxide develops around components that just needs to be disturbed.