[Walt Fricke]

I vote for a manufacturing defect - the center contact isn't centered, so the rotation of the rotor created sideways forces which broke the Bakelite or whatnot the cap is made from, at which point the center contact fell off.

But that's assuming the mold is what places the center in the center - if it is machined in later, then maybe the thinner casting side was enough weaker that it failed?

I love the ball point spring fix. Glad I read this.