The pool pump is driven by a dual voltage single phase motor (115/220VAC) with a 125VAC start capacitor (the motor is set-up for 220VAC; 220V 1P supply.) The motor is started by a 220VAC magnetic contactor (DOL,) but when the start button is pushed the contactor coil won't energize and the contact engages and disengages at rapid pace. I measured the voltage across the contactor coil terminals and it read 140V. No wonder the coil won't energize. Is the drop in voltage caused by the start 125VAC capacitor? I think it takes a few seconds for the motor's start circuit to disconnect thus preventing the contactor coil from energizing.
Edit: Measured both run and start capacitors and both read the same capacitance as printed.
Also measured the resistance across the contactor coil and it is ok as per manufacturer's data.