We don't publish a flat number here because spring cost depends on door weight, spring size, and whether one side or both need replacing - and on a house built around 1960, we often find the original hardware isn't a size anyone stocks off a shelf anymore, which can mean a short wait on parts. Progress's median household income sits at $75,362, a bit under the wider service area's $79,688 median, which doesn't change the job but it's worth knowing we quote the repair, not the neighborhood.
The honest limitation: if the torsion tube, drum, or bearing is worn past use - which shows up more often on older original hardware - fixing the spring alone just buys you a few months before the next failure. In that case we'll tell you straight that spring-only repair is the wrong call and a full hardware swap is the better money.