Did I overpay for this Seamaster?

I am not a collector and bought this on something of a whim. It is a 1982 Seamaster with date. I love the style but wonder if I jumped the gun. I paid about $700. The face looks good to me. Only the six marker is missing the little circle on the outer edge. It looks as if it were replaced with the piece meant for the quarter hours.

What concerns me is these marks on the back. They look almost like welds. Unfortunately, it was hard to see the extent in the seller's photos. Is this evidence of some extensive and/or flawed repair? Or is it just general wear of a forty year old watch? I am curious what that is and if I should do anything about it.

Either way, I am still thrilled about my first Omega, and you cannot see any of those imperfections when wearing it!

The black marks gave that appearance to me. It makes sense that it is simply the plating having come off.

Seller does not accept returns-what a red flag I ignored. Could try to get it back through the ebay service. That said, I still like it. I am not against getting my use out of it. Unless I have really been had that badly.

Thanks for taking a look!

edit: the add did state it was in excellent condition..

Thanks for the advice everyone. I am going to return it, and will definitely check out that thread there on my hunt for a proper one.

If it was only on the back of the lugs, I'd be more ok with it. I usually see these in good condition for $1,000+ but I am not as well connected as some other members I'm sure. You could try though the Ebay returns if it was described as excellent, there is clear wear of the gold plating. I also think some lume plots are missing, there should probably be two at the top of the 12 o'clock marker, and the 4 o'clock seems to be missing but that could be from the photos.