The two plastic hinge mechanisms must be oriented as shown to fit into the base of the keyboard.
Snap the plastic tabs on one hinge piece into the plastic socket on the base of the keyboard. In this example, the right hinge is being put into place first.
Repeat step 2 for the second plastic hinge piece, on the left side of the socket. The completed hinge assembly should look as shown. To fit the key on easily, try to make sure both hinges are moved in towards the center, all the way back into their sockets.
Each key on this type of keyboard has a metal bar under the key that provides additional support. The metal bar should be attached underneath the key as shown. It simply snaps onto the key.
Insert the ends of the metal bar into the lower outside notches in the keyboard socket.
If your keyboard is missing the rubber spring piece, place it in the center of the hinge assembly. It will be held in place by the surrounding key and hinge.
Align the key on top of its place on the keyboard, and press down evenly. All four corners of the key should click into place.