@And1 Your new pictures are not yet free to see for other users. But on your picture from post 1 it looks as if it is the silvery shinig soldering point with a deepening or hole diagonal above the C letter from the DC inskript. If you still have the socket and put it into place where it was, you could locate if the central positiv pin coming out horizontally at the inner end was rectangular bent and pointed to that silvry shining deepening hole. An as I said before, the hole also looks a bit burned; maybe in the multi-layer print not all contacts inside might profit from soldering the positive lead onto the silvery shining solder point with the central hole next to DC. daddle
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