FWIW, my neighbor has PDPs, and when I played his kit, the same thing happened to me. Since I don't have a vested interest in his pedals, I never really looked to see why that was.
Now that I've seen your pics, it's obvious to me something's wrong, either with the design, or the setup, albeit I suspect you do indeed have them assembled properly. But, look at the angle of the footboard. That's awfully steep. Do a search for DW5000s, for example, and you'll see that your pedals' angles are easily much steeper, as is the beater "throw".
Based on the design, adding links to the chains would lower the footboard angles, yet likely do nothing for the beaters leaning so far back. It almost looks like to me like it's just a poor design, although if they're heavy, the weight of the beater heads could potentially cause the cross-shaft to rotate too far back. It looks like you have the beaters extended all the way out. What happens if you lower the beaters? Does it change that absurd "throw" of the beaters? I suspect not, but it's worth trying.
Also, just because you got them on eBay does not mean you cannot resell them on eBay, and get others, if you can't resolve this issue.