It is easier to work on this type of unit by first removing the entire ice maker from the freezer compartment. The unit is usually mounted to the freezer case by two or more screws. Remove the bottom screws first. While supporting the ice maker, remove the remaining top screws. Unplug the ice maker from the freezer cabinet if you have not already done so.
Along the edge nearest the shutoff arm, a pin protrudes through the mounting plate (labeled "A" below). The arm pin has a spring under the mounting plate. Reduce the tension on the spring by moving the shutoff arm into the "on" position, down, against the ice maker.