First thing I do is remount the egg crate up as high as I can with new fasteners like plastic or metal bolts. Not the pop in ones.
Much of the sag is caused by the crate being loose.
I have then added some foam to the top of the crate and shaped it as neded.
Then get the nose very warm in the sun as noted above and reinstall.
Has taken care of the sag most of the times.
[This message has been edited by Dodgerunner (edited 05-23-2014).]