This is a good article but I've found that trying to reheat the butyl rope to get the sound insulation stuck back to the door frame doesn't work very well. I recommend removing the old rope and using new rope with a heat gun. For removal I use Acry Solvent by Transtar. It takes time and patience so as to not make a mess but leaves a nice clean surface.

I also recommend replacing the sound insulation if the existing is compromised. It's more than sound insulation as It keeps rain water draining down the window in the door and out of the interior. This is also another reason to replace the butyl rope.