Hi Uncle Bill!
We used to see a lot of these many years ago. Rio used to supply a
water clear epoxy and the chips. I suspect they still do. If not try
IJS in Gallup NM. they will have it as well.
We used to burn out the old damaged goop, clean the recess REALLY
WELL, just mix up the chips and glue then overfill the recess and
grind back to level. Sometimes when there was decoration in the way
that would prevent grinding, we used modeling clay and made a little
mold just larger than the recess. We would pour the epoxy & chips
into the mold and let it harden then clean that up, grind to size
and epoxy it into the recess. Those are a little harder fix. If you
have to go that route make sure the mold is level and has a nice
flat bottom as this is a real timesaver. Make the piece thicker than
you need as well.
I suggest you skip the super glue. Others may have a method using
this that will work but I have never seen any that didn't yellow and
we always found it the pits to mess with.
Good Luck. Dan.