That is a toughie. If the detached dial face is at all flexible I would experiment with some 3M 77 or 3M 78 on a flat toothpick sanded or shaved razor thin that could be coated with the adhesive and then slipped under the separation about 2-3 mm.
Then is has to be smoothly backed out followed with an immediate compression of that spot with an old reverse spring clip clothespin faced with a bit of poly (zip-lock) bag material that does not stick to either the adhesive or the dial face. Let it set 3-4 hours at least and see if it worked.
I can send the clothespin, I have some left over from the "old" (Model airplane) days. You need to find the rest.
Posts: 6492 | Location: Southern California in the USA | Registered: July 19, 2007