A method of the present disclosure includes of repairing a core stiffened structure with structural foam. Simultaneously with the arrangement of the FFC on a vehicle-body-panel-side portion of the roof trim, the room lamp is mounted in the lamp mounting window. A DC-to-DC converter converts the back electromotive force from the spinning disk into voltage which drives the retract circuit. A magnetic piston is slidably received within the valve housing, however, the longitudinal grooves permit liquid within the reservoir to travel past the magnetic piston.