An actuator, coiled compression spring, and abutment surface or pair of stationary contact surfaces trap a contact roller. The spring shifts relative to the roller, assumes various contorted configurations, and whips the roller along actuator cam surfaces to stable roller positions. Also disclosed are means interlocking a shaft and switch actuator; a rotatable and axially movable switch actuator; and an actuator and shaft that snap together with means that prevent subsequent separation of the shaft and actuator.