The LED fixating light of the Zeiss 30sl/m slit lamp is used with the keratometer attachment to measure K readings. The small BOX on the left of the slit lamp has a cable that goes into the body of the slit lamp. There is a black wire inside this box that has been cut and is causing an open circuit , thus, making the LED not light . Which port inside the box , 1, 2, 3, 4, or 5, should this loose wire be connected in order for the fixating LED to work?

Equipment: Zeiss 30sl/m slit lamp