So I've been building a strat from parts over the last few months and I cannot seem to figure out these locking tuners (Gotoh Magnum style). All instructions were followed properly during installation and post height adjustment has been fine but ultimately the post does not turn when I turn the peg after unlocking the string hole with the screw slot on top. as per instructions!

Now I've googled the crap out of this and can't find where I've gone wrong, it feels like one of those painfully obvious things that I'm overlooking but hopefully y'all can point it out in any case!