When the Atari VCS (2600) was launched in 1977, it came with the CX10 game controller. Fairly soon, it was discovered that the controller is costly to mass produce and the long stick travel made gameplay unnecessarily difficult, so CX10 was replaced by the visually similar CX40 model only about one year later.
The printed circuit board inside the CX40 is much simpler than in the CX10. It consists of metal contact strips with concave metal cups on top. They are held in place by a layer of tape. When the pin at the bottom of the joystick presses on the cup, it buckles and joins the connectors. This is known as a membrane switch. Meanwhile, the CX10 uses metal strips with a spring-loaded plastic mechanism on top.
The CX40 was cheap to manufacture but not very durable. Metal fatigue made the contact cups come loose over time, and the tape holding the arrangement in place was not exactly built to last, either. In the press, membrane switches were already referred to as antiquated in the mid-1980s. The CX40 controllers that you can play on have “lifetime upgrade” circuit boards designed by Bradley Koda from California. They try to work around the problems in the original construction without significantly affecting the feel of the controller.