Tin Man

S1, E18: O'Neill and the SG-1 team arrive on PX3989 only to be zapped by an electrical trap that renders them unconscious. When they awake they find themselves in an underground lab with Harlan a strange but apparently peaceful native of PX3989 who claims to be 11 000 years old and who says he has not only fixed their injuries but improved them. When they return to Earth over Harlan's objections the team members discover what he means. While they all feel like themselves they are all now machines that have been implanted with the consciousness of the SG-1 team members. Worse they will run out of power and die unless they return to PX3989. Upon their return they confront Harlan who as a robot himself is mystified by their demand that he put them back in their human bodies and sacrifice their immortality. Under pressure he takes them to meet themselves in hopes of achieving a compromise between man and machine.