I was soldering a board yesterday and everything was going fine. Then, for no reason I could see, one joint would not solder! All the joints before it were OK as were all the joints after it.
It was a manufactured PCB and the component was a through-hole T092 tranny - this happened on only one lead - with quality multicore solder and a Hakko FX-888D.
The solder simply "climbed-up" the lead, away from the pad as if allergic to it! Neither flux nor masses of solder helped.

Eventually, it worked after trying time and time again.
Why on Earth does this happen and what should one do about it?