As I mentioned in the previous post, the S2 screen needed replacing because it was scratched. Replacement S2 screens can be found but are usually expensive. I did buy a used one from a well known UK dealer but, when I got it, it was also scratched so it went back. They can be found on ebay, usually from Far East sellers, but can be anything up to £60 or more.
The same screen type is used in the Contax 167 and the Aria so finding a broken 167 or Aria might get you a good screen but the cost is likely to be no better.
I investigated a number of other screen types to see if they would fit and, believe it or not, the 139 screen is perfect. Because the 139 screen isn't user replaceable, there's no tab on it so fitting it is a bit more difficult but the size is the same.
One good thing about the S2 is the screen is aligned by its top surface which is the surface which the image is formed on so any slight differences in screen thickness won't affect the focus. Other cameras align the screen using the bottom surface so the thickness has to be correct to get the top surface at the correct distance from the lens.
So if anyone want's a replacement S2 screen, a 139 screen may be the cheapest answer.