Case studies of six federally inspected pork slaughter plants were conducted to determine the causes and solutions for problems with return-to-sensibility in pigs after electrical stunning. Pigs were held in a V-shaped restrainer conveyor and stunned with a manually applied head-to-body electrical stunner. Within each plant, 100-200 pigs were scored based on stunner positioning, squealing when stunner was applied, and signs of insensibility. Spontaneous eye blinking after stunning (which indicates the pig is beginning to return to sensibility or that insufficient amperage was used) ranged from 0.5 to 7 percent. Signs of possible return-to-sensibility disappeared before bleeding pigs reached the scalding tub. Eye blinking was eliminated by improving bleeding practices, redesigning the stunner operator’s work station to facilitate proper placement of the stunner, redesigning the head electrode to improve proper placement, reducing line speed, improving initial contact of the stunner, and increasing amperage (that was too low for sows). Correct electrode placement, appropriate amperage, and bleeding procedures need to be monitored to ensure the pig is rendered insensible. It is possible to correct problems with electrical stunning, but the procedures need to be monitored. Spontaneous eye blinking (without touching the eye) is recommended for evaluating return-to-sensibility problems under field conditions.