If still under warranty I wouldn't open it at all. -6 is within tolerance and definitely acceptable.
Another happy stylist owner! Is yours manual wind too? They are from the 70s usually. The movement in mine is called Tissot 2141 wich is also called Omega 625.
The Omega 625 watch movement was produced from 1973 to 1979, with a total of 2,410,000 units manufactured. It shares numerous components with the automatic family 670. The movement features manual wind functionality and is equipped with Incabloc Shock Protection. This information is based on the provided facts.
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