As you may recall, Brumby accidentally broke one of the small green buttons on an hp 1740A. I was investigating the same type button (not green) on an hp 3457a. I wanted to compare it to a CAD file I found here on Thingiverse -
https://www.thingiverse.com/thing:3057821But simply pulling it off with my fingers collapsed it. The plastic on these older parts is becoming very brittle. I went ahead and printed the button using a resolution of 0.1 mm and it fit well after a little trimming inside to remove some stringing. I printed the test button out with translucent PLA for a test because that was what I already had loaded.
Later I printed it in white and made some for extra parts. Some hp buttons on these older models are white, but this button and others like it of this era are not pure white, but it looks to me rather a very light almond or cream. Yet it does look good and I think it's fine. I haven't found that exact cream color PLA yet. I suppose you could paint it too.
As far as the green, there are LOTS of green PLA to choose from. If one button sticks out because of a slight color mis-match, you could print out all the buttons that constitute a vertical column. Or, like on yours, you could make the printed button the "Sweep After Delay" button because it is sort of by itself. But then you risk busting other buttons mucking with them.
Good Luck Brumby, now you have a project (as if you needed more). Look forward to the pics!