The feet on the keyboard are made of plastic, soThey often break down. You can make broken legs by soldering them with something hot, with the same soldering iron or with a heated nail. But this option will be short-lived, and will have to breathe the toxic smoke of burning plastic. Therefore, it is better to replace the keyboard feet with metal hinges from the usual clerical clamp. It can be bought in any specialized store, and very cheap. The main thing is to guess with the size, since not every clamp will fit your keyboard.