If the seal is broken on a double-pane window, the windows need to be replaced. In order to replace the windows, remove the window sashes and peel away the gasket from the old windows, then put in new windows and use silicone to adhere the gasket and seal back in place.Continue Reading
Use the following steps to replace double-pane windows.
Unscrew the windows and tap the windows away from the frame.
Peel away the gasket from the windows, making sure the gasket does not rip.
Put in the new windows and seal them using silicone.
Reattach the frame around the new windows and gasket. Make sure silicone is filling any gaps in the seal.