See picture.
Pin 1 of line filter goes to Pin 1 of power supply plug
Pin 2 of line filter goes to Pin 4 of power supply plug
Pin 3 of line filter goes to Pin 3 of power supply plug
Pin 4 of line filter goes to Pin 2 of power supply plug
Ground pin of line filter goes to Pin 6 of power supply plug (and to chassis ground)
Pin 5 of power supply plug is unused.
Power supply plug as viewed from top of scope (pin 1 is towards to rear of scope).