The most common misstep on a door this age is ordering a panel by width and color alone and finding out on install day that the rib spacing or hinge placement doesn't line up - steel sectional doors made around 1979 weren't standardized the way panels are now, and a near-match isn't a match. The second way this job goes sideways: swapping a single heavy insulated panel into a door where every other section is the original lighter, uninsulated steel. That throws off the spring tension balance, and the opener starts straining on a door it used to lift without effort.
We've also seen owners try to stretch a patch repair - screwing a brace across a split seam - past the point where it's worth it. Once the steel has stress-cracked at more than one hinge point, a patch holds for a season and then fails again, usually at the worst moment. At that stage, replacing the section outright costs less over a year than patching it twice.