MA3 power fix

Found this forum while trying to figure out where to solder a bypass wire for a gateway ma3, and noticed it needed pics. no making fun of my soldering job, but it worked!

Here is a pic of where i attached the wire, and some helpful soldering advice would be nice in return, what is the best way to solder the wire to the back pin of the power jack? I had a hard time making it stick to the rear of the jack, would flux help?...