Horn help, old aftermarket wheel

I have a Superior 500 wheel, and I think it is missing something to make the horn work correctly. From left to right; the plastic assembly that bolts to the colume with a copper ring and a wire attached, then the chrome bezel that covers it, then the wheel itself, then the piece the wire connects to, it is metal on the side that faces the wheel, and plastic on the front. The 3 screws hold that piece to the wheel but they bottom out leaving the metal/plastic piece free. Then the chrome center cap just clips on.
Now I am thinking there should be a spring or something that holds the metal/plastic piece away from the wheel, and when you push the center it makes contact and- beep.
But there are no marks left by any missing springs, and there really isn't any room for them either in the center or around the 3 bolts, they would just make contact between the 2 parts leaving the horn on all the time.

How do these aftermarket wheels/horns work?

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