replacing seal that goes between upper grill and windshield

Hope some of you experiance mechanics might be able to help, I have a squeak I am trying to track down and have removed all but the upper grill from my dash/instroment cluster. The squak remains so I know it is on the passenger side of just this one part, I when to take the part off to see if I could find anything rubbing or that would be pushing on the part to make the noise but foind it is attacked to a rubbe seal which is then atttached to the base of the window I did not remove this as they are discontinued parts and I don't know how to propery remove it and reattach it. Any suggestions? You can see the seal in the diagram of this parts catalog