dekhn
3 hours ago
I really enjoy this channel: https://www.youtube.com/@WristwatchRevival He takes watches that need repair, disassembles them to basic components, washes them, and then reassembles and tunes them, replacing any parts that have broken (often the mainspring).
It doesn't have the explanations or the math, but the cameras are high quality and you can really see just how jiggly the balance wheel and spring are, and how the watch will just "spring to life" when you install those bits.