Tudor Valjoux 7750 questions has this happen to or maybe someone could explain?

[Georgevlado]

So I have a valjoux 7750 tiger From 1999 I’m pretty sure it was never serviced.
the watch slowly lost time over the time about two years until the point I was losing 15-20 min a hour.
I stopped wearing the watch and put it in the safe until I got time to give it a service.
a year passes and I’m ready to take it for service so I wind the watch to see how much time it’s losing.
I wind it fully starts running on the 2nd or 3rd turn then give it a shake to get the 7750 wobble.
3 days later im wearing it night and day and it’s still keeping good time can someone give me an explanation still gonna give it a service but I’m holding off now


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