The dial is stamped Swiss made and "automatic" rather than the German spelling with a K.
If the dial has been changed, the burning question is why?
Bracelet looks kind of original, but, badly polished the "S" stamp is correct for some 90s watches, maybe there is a manufacturing detail on the clasp, I think NSA where oem.
I've found the Sinn service dept very helpful and their work reasonably priced.
I'm sure there will be someone who is a real Sinn expert who can comment.
The 103 is a great watch & if it was daft cheap, why not?