Originally Posted by wonwinglo

***Well Jim in my toolbox is a very old tin of Fluxite ! the contents are discoloured and gungy,but the paste still seems to work,however who knows the shelf life of some of this material as you say ? it could be that there has been some reaction within the solder to make it do that ? as these things are acetic/acid/caustic based products that work chemically when heat is applied it could be that those qualities have been destroyed with time,try using a piece further on within the coil to see if that does the same ? just a thought.
Failing that it will make some useful ballast weight !