I had some of those extension lockers come open when I had to take it out for a servo gear replacement. I wont say the name as it could have been a random chance and it was also a bought plane.

I normally take dental floss and loop it through the wires so that it is two wraps around the connectors, end to end. I will then tie a knot and apply CA to the knot. I would think that if you pull hard enough to break the floss you have broken the connectors as well.