I had a difficult time finding visual guides for the gasket replacement of the creation windows. So I decided to create a reply to this topic to help others as they work on their Airstream.
Yes, you can identify the creation windows by there insignia in the lower right corner of the movable window. You can see the logo in front of my hand.
You can also see that the original gasket has shrunk and has pulled away from the corners. Here's another picture.
To get to the old gasket and clean off all surfaces, it is easiest to remove the window that moves. This can easily be accomplished by removing the lock washers from both sides of the down arms.
Now the down arm can be disengaged and the movable window can be swung up to A horizontal position and slid out.
The offending gasket can now be pried out or pulled out. My windows had an additional flat gasket that was applied next to The original gasket. I have no idea where that came from.
Once the gaskets had been removed, all services must be cleaned completely. I scraped with a flat bladed screwdriver and cleaned and scrubbed with isopropyl alcohol. I was able to clean and reapply gaskets on all four side windows in one morning.
The gasket material I used came from airstream at Jackson Center. It is a D type open cell foam rubber, 1/2" on the adhesive side and 3/8" high.
There is a channel at the top of the window opening.
I decided to fill this channel also with the "D" gasket. I have a diagram of the window removal process in an Excella owners manual. It shows a "D" gasket there.
I did not replace the old gasket. I simply placed the new gasket all around. Once it was in place I rolled it down to ensure adhesion.
I appear to be out of space. If possible I will continue in another reply.