The windows on the 69s and others are tricky.
On the arm it self us a press on ring. It slides on and off. Yes you might scratch up the arm trying to get it on and off. I put a small wrench on the back side and slowly tapped it off. If you loose the ring or break it you can by more. Most hardware stores or auto parts carry them. Sadly that's the easy part.
Once the arms are off, you have to tilt the window way way up, something like 160 degrees. Then the window can be popped out of the track. Getting it back in is a real chore. From reports its a 2-3 man job. I have been putting off this job for a while. From what I've been told, you have to re install the window at the same angle you took it out. It's curved, so you have to put the side in the track first then pop in the center by hitting it with the palm of you hand or a rubber mallet. One window did fell off in my had as the rivets finally failed. So I used pop rivets from the back side, topped with probond. They look odd but it works.
Now the gasket is usually placed on the window frame, but it can be placed on the sash. It's not considered the best way, but it has been working for me.
I left the window in place, scraped off the old gasket, and adjusted the latches. Keep and eye on these, they can be tricky. Here is where I placed the new gaskets. When the dry season comes, I might stir up enough courage to pull them out and do the correctly. Also the VAP discussed this process awhile back. Collin did a good job explaining how to do it.
I hope this helps.
Not all those who wonder are lost.