IIRC, you can't push in the rubber screws. First, take the fan seperately and put in a screw until you can grab hold of it on the other side, then pull it through all the way. Repeat for all 4 holes. Then put the fan in the case and carefully align it with the holes so that you can pull each screw through the holes on the case. Once you have it all aligned, PULL on all the ends of the screws until the little flange pops through that will secure it in place. Then cut off the ends. Again, this is all IIRC.