I still need photos (but it sounds like the post prior to yours will be posting them), however, take photos as it seems there aren't many documenting this deed... which should be painlessly easy... unless your mast suffered any sort of damage from impact.

If your new antenna mast won't completely retract after replacement you will need to remove the entire antenna unit and remove a peice of metal that can break off on impact from the old antenna, then the new one will fit nicely. If you have any questions (should you run into that) I can provide a better explanation.