Upgrading from 4 GB to 16 GB (OWC), I applied too much pressure and snapped the upper memory stick retainers. The upper retainers appear to be screwed to the board and not connected to the sockets. Lower retainers are fine and appear to be part of the socket assembly. Unfortunately it's the uppers that hold the sticks down and parallel to the sockets. Only pictures I've found are of earlier boards in which retainers and socket are one piece and part of the board. But this model has two screws on each upper retainer and there's an obvious gap between retainer and socket. As Apple applied an extra layer of insulation to the bottom shell over the sticks, I added a few more until the sticks were held down at the correct level. My kid's has used it several months at college with no ill effects. Does anyone know if the upper retainers with the screws are service parts? Or of a better jury rig? Amazing that the machines functionality depends on two skinny pieces of plastic. I'll admit to being distracted by the neighbor's leaf blower just as I was spreading the retainers. Apple Store will be my last resort as I'm triple the age of their employees. I wanted to buy and get out, and finally resorted to calling the manager on the phone from inside the store. (Had Macs for 20 years)