Aging springs and rollers
Across the wider service area the median build year sits closer to 1982, so Andover's stock is a decade newer on average, but newer doesn't mean untouched. Thirty-plus years on the same spring and the same roller is where this job goes sideways: a cable frays, a spring loses tension gradually instead of all at once, and the owner notices only when the door won't lift evenly or starts dropping fast on one side.