Soldering the connectors on the motors is not easy! You have to use an alligator clip to hold the connector in place. Find the hole in the side of the connector and use it to get the soldering iron into the center. This requires a fine soldering iron tip. Fill the center with solder. Stick the wire into the hot solder. I also bent the wire over so it fits tightly first of all. I should have stripped some more insulation off first.