No Plastic flap on SIM/Front Facing Camera - how to fix?

Hey guys,

i bought a defective iPad 2 on ebay but the guy who owned it before seems to have used wrong tools.

There is no "plastic flap" which holds the cable in its place anymore - so the cable is not able to make contact..

Foto of Plastic Flap (c) by iFixIt

(The black small "flap" is missing)

As a workaround I put a small piece of paper under the cable - now it works partially - front facing camera works, SIM is still not recognized. But I want a bulletproof solution ;-)

What should I do to fix this?