The quicker the glue sets, the weaker the bond is. Just a simple fact. Use a high quality rubber cement sparingly and expect to do it again about 6 months later. Rough up the metal surface as much as you possibly can before applying rubber cement.
The "disintigration" of my ED3's started the same way.......eyepieces, then it worked it's way around to the rest of the armoring, which pretty much just started peeling away from the body. No amount of glue and cold water could hold mine together.