Flat-pack hinge oddity

No, it hasn't been junked. It's waiting until you buy a pair of new hinges and will then miraculously reappear somewhere where you were absolutely sure you'd already looked.

... and/or of course the original hinge's problem will miraculously disappear! :-)

clearly I have found my people :)

Oh no it won't! Sod's not that stupid as to allow the mere presence of handy spares to ensure against the need of a repair job to introduce yet another set of problems into some poor soul's life.

Seriously? :-)

Now if it had been irritating your wife, WD-40 would have been applied by now.

WD-40 is not a lubricant to any great extent. The ultimate stuff for unsticking stiff or siezed metalwork is automatic transmission fluid. I'd apply a drop or 2.

NT

I don't think it's stiff or seized ... metal is shine and clean. "Something" has failed where I can't see it. It looks like the spring force is held by a curled leaf of steel ... I suspect it's fractured inside where I can't see it.

That's happened to quite a few of ours (they are quite old). Local ironmonger supplied new ones - five minutes - job done.

You might well be right, but your original description is not inconsistent with a sliding interface that is sticky in one direction. And the thing about WD-40 is that a quick spray will distribute it around everywhere. I agree that ATF is a good penetrating lubricant for metal. But IMHO WD-40 is quite effective for many combinations of metal and plastic, and it will help to free up rusty metal parts.

IME broken parts in kitchen hinges are usually revealed by that hinge no longer locating properly, but the only way to be sure is to take it out. Designs and dimensions are fairly standardised, even if there is no exact replacement it is usually not difficult to find something which works.

But I would still start with a quick spray!

If you want to lubricate it, use a lubricant. It has a lot better chance of working. But as said it probably needs a new hinge. Easy to fit, but there are different versions available.

NT

WD-40 and the cheap clones contain a few percent of mineral oil with a viscosity of a couple of hundred centistokes. A perfectly adequate lubricant for something like a hinge.

and lots of white spirit to wash it away! You might find it works, I couldn't with a straight face recommend it as a lube though. Baby oil, engine oil, any sort of mineral oil is far more effective and far cheaper. And less toxic.

NT