I looked up the Super pump parts list and realized that what I called the pump pot o-ring is actually called the strainer cover gasket you caught me before my edit.

Open the strainer cover, examine the gasket and seating sufaces. clean as necessary.

Could be one of the driain plugs leaking. I'm not sure if thery're both on the suction side of the pump.

I've read about someone using shaving cream to look for suction leaks.