Think @scott o was talking about hanging the lights, not extending them from the flex arm. Is that right?are you missing one of the hex stand off spacer screws?
pretty sure you can get them cheap at HD or Lowes if you need it right away. I think amazon even sells them.
i think they are M3 6mm threaded but not positive. Zach may be able to confirm that though.
The hex stand-offs work like a charm, though, for extending the length of the flex arm.