What goes into the threaded hole in my dash light (mine is obviously missing)?  Is it just a threaded machine screw, or something else larger to effect the opening/closing function?  Any idea of thread specification or a source for this part?  (Photo attached - bad lighting - looks like brass but is chrome.)

My dash has the instrument light installed in a square hole at the top of the dash.  Below that is an empty round hole.  What is installed in this second hole?

Thanks,

John

I've attached a photo of my dash.  The square hole matches up with the dash light.  Any ideas what goes into the second round hole?