I looked over the vent window tech tip sheet and still don't get it... to me it does not appear that you can remove inner piece (that the glass attaches to). I took off the nut and spring but it doesn't look like the section will come out... see pic.
http://www.tj-mac.com/66chevy/images/ventwing.jpg

The replacement seal has only a hole, I don't really want to slit it to go around that stem... see pic.
http://www.tj-mac.com/66chevy/images/ventwingseal.jpg

Anyway, any help, suggestions appreciated.