[captain harlock]

I just fill the soket plugs with solder and tin the wires with solder, too.

That's why you need to use a very capable soldering iron with high watt rate and large flat tip.

Those sokets seem very dogmatic when you use normal soldering iron, and I almost destroyed one of the sokets with my pie** of **#t 40w Weller iron.
Although my 60w Goot iron has a pointed head tip, the solder was easily molten( but went through the " schizophrenic melting"), though the process would've been many times better with a high end soldering system with a chesil tip.