This happens once in a while. I bought from the same seller, and he actually sent me two pairs of adapters (score!). Three of the adapters (one full set and one more adapter) are perfect, and one has a problem similar to what you're showing. It's not as bad - I have it back in place and it works, but I have to push the middle portion together when I'm sliding the adapter into the watch. Looking at the pic you supplied, I can tell I'm missing the spring that attaches to the middle peg of the black piece. I have two tiny springs for the outer pegs of that piece.
From what I've heard, Freedomoclock is very good about replacing faulty parts. Since mine work, and they accidentally sent me an extra set, I'm not going to bother them about my faulty-ish one. The one I paid for works beautifully, and even the faulty one works just fine.