I just had one of my windows out, to get an estimate for fixing the snakes between the layers. Under the rubber strip are #2 Robertson screws, every 4 or 5 inches. Three of the screws are bigger than the rest, so you need to sort them as they come out. Once the screws are out, there is nothing else holding the window in, so be sure there is someone outside to catch it. Mine hung up on a thin bead of silicone someone had used across the top, to keep the water out. Other than that, it was a very easy removal. Then getting the glass out to make a template, required removal of a strip of steel that holds the aluminum frame together across the join, fastened with 4 small screws and lots of black rubbery caulk. One more screw, in each end of the post that separates the panes, and it all falls apart. So easy that when the new glass is ready, I plan to install it all myself.
