for a vintage piece, at least in my opinion, as long as the visible aspects of it retain their originality and patina that’s what’s most important. I’m not sure how that translates to the value should it go on the auction block, but in my case the function was far more important than the auction value.
See, for me, I'd rather have a watch with a pristine service dial than a junky, patina'd original dial. I don't buy to re-sell though, I just buy to wear for myself.