The most difficult part of the process, as mentioned is fitting up the antenna platter again. It has an explanation.
You have to make sure hard drive (primary one, the one on the top), is correctly fitted. You can make sure it is by matching the screws on the hidden part, on the mounting holes of the plastic hard drive chasis. Once this is matched, it fits perfectly and screws are perfectly aligned.
Just keep calm, and be patient, all parts have perfect milimetric match. IT'S NOT DIFFICULT! PERFECT GUIDE!