Dissasembling windshield frame

Hi all-
 
I have a replacement windshield frame for my 1500 "roller". I need to
replace the glass since what's in it is broken in 3 places. The rubber
here is in decent shape. I want to pull it apart without bending the
aluminum rails, and so far the old gasket is pretty solid in there. Any
tips?
 
TIA
 
-=Chris