Uneven spring tension symptom
It shudders on the way up, or it drops the last foot instead of settling. On a 1990s-era insulated steel door, that's almost always a spring that's lost tension unevenly, not a track that's bent. Because these doors are heavier than the wood doors from decades earlier, an underpowered or tired spring shows up faster and more obviously - you'll feel it in the remote lag before the opener even engages, and you'll hear a grinding hesitation at the top of the travel.
