Panel replacement starts with matching the section - width, height, and whether it's insulated or not - to what's already hanging. On a 1970s-era door that's never been touched, that can mean the exact panel profile isn't made anymore, so the choice becomes a close match on one section or replacing the full door. We pull the damaged panel, check the hinges and end stiles for bending (a hard hit on an old thin-gauge panel often tweaks the hardware around it, not just the steel), and reset the track alignment before the new section goes in. If the rest of the door is original and in rough shape, we'll say so plainly - sometimes one new panel on an otherwise worn-out door is a short-term patch, not a long-term fix, and we'd rather tell you that than sell you a mismatched panel that looks off in two years.