SX-200 will not start

A pump that draws no current on a start demand has not failed mechanically — nothing has reached it. Work outward from the motor rather than inward from the panel, because the expensive diagnosis is the one that starts by assuming the winding is the problem.

Confirm the demand is real

Check that the level signal is actually calling. A float that has snagged on the wall, or a level transmitter reading a fouled sensor, presents to the operator exactly as a pump that will not start.

Check the protection first

Thermal contacts and the moisture-ingress relay both interrupt the control circuit rather than the power circuit. A tripped thermal that has since cooled will present as an intermittent no-start, and clearing it without finding out why it tripped is how the second failure becomes a winding failure.

Then the contactor

Measure across the contactor with the demand present. Voltage in and none out is a welded or failed contactor, which is a ten-minute repair. No voltage in returns you to the control circuit above.

Only then the motor

Insulation resistance to earth below 1 MΩ indicates water ingress. Do not megger through the control cable.