Follow exactly what MacAllock and Gary said. I couldn't say it better.
Another tip: When you are ready to re-asemble, place the screws in the holes and make an anti clockwise movement applying a light pressure on the screw (using the screwdriver). When the screw is in the "perfect place" you will sense a "click" and it will lower itself just a little. This will ensure that in the most part you will be using the original grooves, thus avoiding stressing the plastic any more.
Theodore