Access is gained with the main casing lid removed. This unit is an expensive item and is held in place by two metal fingers which are spring loaded. Precise location of the cell is ensured by two cone sockets in the cell base which locate onto matching cones on the cell slide.
To remove the cell, hold the body of the cell (not the optical surfaces) and lift each finger away from the cell and to the side of the cell and not to the rear where the fingers might contact the optical surface. Mounting is the reverse of removal. Ensure that the cell base is correctly located on the cones.