Well, it does not sound like we are doing things that differently. First I used emery cloth (sand paper) and scratched it up good and shiny, next paper towel with rubbing alchol to clean it. Tried plumbers flux first. (paste I dipped the rod end and clevis into.) Next tried the liquid flux. (clear liquid fluid) heated up with the 140 watt soldering gun. I thought I must not be getting enough heat so got a new tip and finally a propane torch. Maybe it's the size of the solder???? the electrical stuff is super thin and flexable where the silver stuff is 3/16" dia and stiff. ??? maybe the solder is so big it disapates the heat the smaller 4-40 rod can hold ????

The 63/37 is that the normal rosin core electrical solder? Is that what you have been having no problems with?

Thanks