It looks like the cord magnets are still stuck within the systems side connection. If you look at the DC In-Board part you can see the face is smooth along the connectors surface (plastic) and doesn't have these four? magnet pieces stuck to them.
Carefully lift them off (currently stuck magnetically) or just replace the DC In-Board it does look like iFixit is out of stock here's a second source [https://www.thebookyard.com/product.php?cPath=39_1263_288&products_id=6301|Unibody MacBook Pro 13"/15" DC-in/Magsafe Board (09-12)]