[Crex]

Haven't used solder in a long time, so probably get better advice from makers' that still do. I used Sta-Brite back when I did, but like Chris, found it a royal pain...when spots came up long after finishing the knife. There maybe new product out now that has resolved these issues.
Paying more attention to tight fits with good seal of epoxy solved this for me. My knives are constructed such that their handles have to be destroyed to remove the guard.

Your dad was a smart man.

(How's the fishing in your area?)