I'm going to make a high resolution scan of the good dial in our set. I've replaced broken glass in other sets by doing the following:
1) Use Photoshop to clean up the scan
2) Print it on matte photo paper
3) Take it to Kinkos and have it copied onto thin plastic stock
4) Have a piece of glass of the proper size cut at a glass shop
6) Attach the plastic stock to the back of the glass using tape at the edges where it can't be seen.
The result was pretty good, and looked like the original unless you did a very close inspection.
If you'd like a copy of the scan, let me know at
[email protected]