tale of $5.28 wasted....

"I tried to solder to the input of the voltage reducer slots and the dang things wouldn't solder."

Sometime the soldering iron either "DOA" or "POS".. Get a proper soldering iron "one with temperature control" with tip to accommodate the area to be solder. The bigger the area, require bigger tip and vice-verse. Add some flux or solder paste due to old solder joint.