Product review (4 stars): Fixed My Door Leak
This gasket is easy to replace... no tools needed.  I found that I had redo the installation of the gasket a few times until I got the gasket to fit just right in my door.  The tricky part was the lower corner on the right side.  The gasket is supposed to bend into a corner and conform to the shape where the door meets the body.  This was a little bit of a pain to get right the first time I tried to fit it in.

There are a bunch of videos online that show how to do this install.  Dont forget to soak the seal in warm water before installing it.  This made it quite a bit easier to work with.

After installation, the door was harder to close for a few weeks but seems normal now.  I suspect the new seal is a bit firmer than the old one and took a little bit of time to work into place.