A single damaged panel on a steel sectional door is, in most cases, a one-section swap - we unbolt the hinges and end stiles, lift the bad panel out of the track, drop in the replacement, and re-hang the hinges. On a door this old the harder part is usually the fasteners and track alignment, not the panel itself. Decades of mild coastal-adjacent temperate weather here don't crack steel panels the way freeze-thaw cycles do elsewhere, but they do let surface rust creep in at the bottom panel and at any spot where the factory coating wore through years ago. If rust has eaten into the steel at the hinge points, the replacement panel goes in fine but the adjacent panel's hinge holes may need to be re-tapped or reinforced, which adds time to what looks like a simple swap. We check the full door, not just the damaged section, before we call the job done.