Kind of sounds like the flame was a little too cool. I don’t know-
or don’t remember- how big in area you said it was or how big the
bezel cup was so you may be right about the tip you’re using being
too small. Also, did you re-flux it when you came back from the
store? Try the sweat solder technique I mentioned- somebody else
here suggested the same thing. You might want to set it up on a
tripod with an open center to where you can run the flame under the
entire piece so it gets heated more evenly too. When you sanded the
solder snippets did you wash and pickle them first? I tried
hammering some wire solder once too and I found it didn’t flow as
well as unhammered solder. That was my experience anyway.
Kenton