Quoted from RC_like_the_cola:It's weird. I can post pics tomorrow. I find that flux helps alot when replacing sockets. Especially trying to get old solder and new solder to mix if needing to reflow a coil lug or something.
by old and new solder, I hope that by new, you are still using 60/40 lead based otherwise that is probably your issue. lead-free and leaded solder do not mix well due to their chemical make-up and different melting temperatures