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Discussion Starter #1 (Edited)
Longines 431 from 1968/69.
33600 vph ultrachron

I know it's an automatic but I want to get a sense of how worn my mainspring is.
I have hand wound it before (maybe 10-15 turns?). I *think* it started getting a little tight but it could just be me not wanting to break anything.

Maybe I should just buy a winder. Thoughts?

Follow-up question: When fully wound, how much reserve power did the 431 movement have new?
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