If you're serious about mechanical watches or have a small addiction like me, I'd highly recommend buying an old school timegrapher and regulating(link below).

I have a rather ridiculous collection of Orients, and some were off by minutes a day from the factory. Just the nature of them, I guess.

I would just offer to regulate them for other people, but I've scratched enough casebacks to never feel comfortable in that.

Link to example timegrapher: https://www.amazon.com/OTOOLWORLD-Tester-Multifunction-Timeg...