Nikon Nikkor AF 28mm f/1.4 D Lens Repair - M/A Selector Button

Hello!

I'm working on repairing my 28mm 1.4 D with a broken plastic M/A selector ring. I have a metal ring replacement already, but am missing the extremely small 'button' that is pressed to release the selector ring and allow it to move.

I'm wondering if anyone has spares or maybe the specs on this small part? Maybe it could be 3d printed?

Thanks!