Anco Deadlocker Windshield Wiper Arm Install

[geigs]

Hi all,
Just picked up these fine NOS arms at the Charlotte Autofair this past week. My question is does anyone know how to make the end of the arm swivel so that the blades can be adjusted to the correct angle? I know no tools are required and it's easy to do; I just can't figure it out.  Any suggestions greatly appreciated. Thank you.

[Spinneyhill]

I don't know, but the red button and the circular piece might indicate you can push in the red button and turn the circular piece (a sort of turntable?). This would of course require a spring in there under the red button and perhaps a ratchet under the circular piece.