Take the window out. You may have to remove the couplers to get the trucks to swing far enough to get the screws out to remove the shell. Then you have to poke a slim screwdriver in to unplug the light strip. After moving the shell away from the rest of the body, you can remove the light strip and squeeze the tabs in to remove the cupola. Then cut the insides of the tabs so you can remove or replace it from the top since it goes in last after you plug in the light strip and put everything back together after removing the window. It'll be more obvious than this post .