Hi, My friends 18-55mm lens broke - on the backside of the lens there is a small black "thing" which fixes the lens to the camera itself. When you twist the lens onto the house then you should here a "click" - it is secured by two black "things". One of these has fallen off. Question is - can this be replaced by him or does he need to go to a garage? does anyone know what this "thing" is called? Cheers!