Sagging panel track misalignment
That combination sags at the bottom panel first - you'll see daylight at the corners, or the door drags on the track before it fully seats. Openers on these original setups tend to be older chain-drive units bolted to headers that were never built for a heavier insulated replacement, so if you're swapping to a heavier door, the header sometimes needs reinforcing before the new door goes in.
