This is my little tutorial on how to make an My SATA power cable RCM Jig that works for me. Sorry if this is in the wrong section! Sorry for any bad images!

What you want to do is get an old power supply, or have a spare SATA Power Cable. Cut it off.
1709527235759.png

Then break it to get the pins out - or as @Apache Thunder pointed out, lift the tabs, but that's no fun :c
1709527280235.png

You'll have something like this:
1709527319422.png

It has three little pins, so break one off, they're pretty delicate so it should break off easy
It should look like this:
1709527359337.png

Slide it all the way down the right rail, don't force it as you can damage the pins and you don't want that
1709527390703.png

If it don't work the first time, just try and re-seat it, you'll find the sweet spot.
If you find it hard to hold the pin, you could use tweezers to delicately put it into place.

Good luck! as always when it comes to this sort of thing, I hold no responsibility at all, There's many other types of jigs out there, but this one works great for me!