Invention provides improved surgical instrument having end effector mounted on end of elongate shaft extending from a handle. End-effector is capable of several different operations, including grasping, cutting, and sealing and/or coagulating tissue, and one of the operations is controlled by actuating mechanism contained within handle. Mechanism includes drive shaft, actuator and component for transferring movement of actuator to drive shaft, which in turn controls end effector. Mechanism is configured wherein component and drive shaft are assembled via a snap-fit connection, thus providing a simple assembly without need for any additional features. For example, proximal end of drive shaft is provided with flexible tabs arranged to engage with a shoulder within internal cavity of component. As such, when drive shaft is inserted in to internal cavity of component, flexible tabs snap into shoulder and retain drive shaft firmly in place.
