Firstly, ensure you have the right tools on hand. You'll need a screwdriver (both flathead and Phillips, depending on the door), pliers, replacement rollers, and a measuring tape. Replacement rollers can be found at any hardware store or online, with measurements typically provided to ensure a perfect fit.
The Importance of Quality Window and Door Fittings

Electrolytic Two-Step Anodize
Slimline Aluminium Profile A Versatile Solution for Modern Design
Aluminum construction (window and door / wall curtain)
One of the best decisions you can make for the environment is investing in high quality materials that last a long time. By this standard, both cast iron and wrought iron are good choices for the environment because they can last for generations.