Gears soaking in isopropanol after being ultrasound washed.
My first Unloved Watch—that 1971 Citizen with the 21-jewel movement I now know is named the
It felt like a completely different watch when and after reassembling it after cleaning; the balance moves way, way more freely, and in fact it started ticking away for a few seconds just by handling the case, after I cased it. Before cleaning, it was sort of barely running, the balance did move but "heavily," and had clear trouble running when I held it different positions. No more, now it's like it wants to run, and springs to life at the first excuse.
That's a way-cool feeling. Like a kind of magic!