Center and level the first section after you install the brackets. The door must be level even if the floor isn’t, so use shims under the section to level it. The rubber gasket on the bottom section will fill the gaps created by an unlevel floor. To hold the level in place, tape it to the section. To hold the section in place, lightly toenail a 16d nail into the frame and bend it over the section. Add brackets and rollers before setting them in place and stack one section on top of another, toenailing as you go up.
Furthermore, newer doors come with more improved security features, helping to improve the way you protect your home and loved ones. While older doors are easy to break into, whether through breaking the lift mechanism or even using a universal garage door remote, new doors come with many redundant security features, which will go a long way in deterring even the most ingenious burglar.