The conductors look all twisted too much, try to straighten them out or maybe they require a ferrule crimp. The neutral's inserted so how did you get that in?
I have loads of ferrules, but no crimp pliers so often tin the wires with solder, but do you need to put a screwdriver in a hole along side the terminal to open it?
You have either "bunched up and doubled over" the strands of the conductor
or
"doubled over and bunched up" the strands of the conductor.
Loosen the "set-screw" in the socket opening to its maximum safe holding position,
straighten all conductors,
twist them together,
cut of any excess length of individual conductors.
insert in the tapered twisted conductors in the "socket opening"
and then
tighten the set-screw.
I'd certainly cut off and re-strip that cable to fit it with the strands straight.
Presumably the orange lever is pulled . pushed down to open the sprung-loaded terminal? More force needed?
I'd probably use a small screwdriver to push into where the cable goes as well as one to press open via the orange lever in case there's a stuck mechanical bit inside. Then re-try with the softer copper wire.
I have loads of ferrules, but no crimp pliers so often tin the wires with solder, but do you need to put a screwdriver in a hole along side the terminal to open it?
I thought that tinning wires was frowned upon? That said, I think it is only a no-no where cables will be likely to move (and accordingly snap internally).
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