Extension springs over the track
A lot of these houses were built right around 1974, which puts them square in the era of extension springs mounted over the track rather than torsion springs on a shaft above the door. Those extension springs wear out differently than torsion setups - they stretch, the safety cables fray or go missing entirely on homes that haven't been touched since they were built, and the open/close cycle gets jerky before it fails outright.

