Cable rust after thirty years
With a median build year of 1990, most garage doors here are pushing past the three-decade mark where galvanized lift cables start to show rust bloom and fraying at the drum. If your door is heavier on one side when it opens, drops crooked, or you can see individual strands sticking out near the bottom bracket or the drum at the top of the track, that is a cable giving out, not an opener problem.