In any city, in any country, go to any mental institution or halfway house in you can get yourself to. When you reach the front desk, ask to visit someone who calls himself "The Holder of the Grand Pivot." They will try to talk you out of it, to turn you away, but if you insist, they will concede defeat and accept your request, if only to get you to leave.
You will be taken down a set of stairs, seemingly to lead into a moldering basement. There is no elevator and the staircases are lit by ancient bulbs encased in rusted wire frames. There will be a sound as if someone is constantly coming from above or below, but I wouldn't suggest looking back. The steps are worn and rounded, and the walls wet and somehow seeming to wriggle. Your guide will simply point to a door at the base of the stairs, a windowless iron door.
If you enter, you will find what appears to have been a padded room, with the walls, floor, and roof bare, exposing cold metal. There will be a repulsively fat man sitting, reciting the Lord's Prayer. The man will only acknowledge one question. "I am a man of the Lord, what turns upon the pivot?" The man will explain in a thick Russian accent what will occur when the post and pre halves join. It will be a by-the-minute account of the exact day, save the last 5. He will then return to reciting the Lord's Prayer. If you ask to see the pivot, he will violently attack you; you might notice his pared-away nails and the small, revolting bulge under his jumpsuit. If you claim to be the smith, he will remove the pivot from his jumpsuit while crossing himself.
This is the centerpiece of the 538, the 55th item at the core of them all. They all turn upon the pivot, and now that you possess it, so do you.