Hi Dennis,
In viewing your posted photos, I saw this question that went unanswered and I apologize for missing it-
It is extremely difficult to repair enamel on antique pieces - one reason being that you don't know what brand or color code and not all enamels are made the same - I would suggest, removing the old and going in with the new.
Dennis,
You can also look on the Main page under the "Links"tab - Enamel Repairs, there is a company in Rhode Island that does antique enamel repair-
I buy a lot of antique watches in the course of my business, very often with some damage to the guilloche enamel. I can fix the watches so they run correctly, but have had no luck with being able to repair the damage to the enamel. Short of removing the enamel and starting over, are there any tips on how to do this? Thanks, Dennis