Hey Gang! Does anyone know what the GRAFLEX Red Button and Glass Eye thread size/pitch is?

I need to buy a tap to adapt a Red Button to a GRAFLEX style TCSS MHS Blade holder but I'm having difficulty finding the info on the threading.

Just to be lightsaber crystal clear, I'm trying to adapt a working GRAFLEX Red Button by drilling out the whole and tapping it so that I can screw the button into the blade holder and wire it to be a functioning aux button. I'm not looking for the 10-32 threading of a Red Button Thumbscrew as that's already drilled and tapped there from TCSS.

If anyone knows the answer, please let me know what it is.