We'll say this plainly: don't do a torsion spring yourself. The wind-up tension on a standard residential torsion spring can break bones or worse if the winding bars slip, and a lot of Elmhurst garages still have the original bar and cone hardware from a 1964-era build, which means old, work-hardened steel that doesn't behave the way a spring from a hardware store kit does. Extension springs on some older single-car setups are a little more forgiving to inspect, but even there, replacing one without the right winding bars and clamps is a bad trade for the cost of a service call.
What you can do yourself: check whether the spring is torsion (mounted horizontally above the door, on a bar) or extension (stretched springs along the upper tracks), take a photo, and note if the door came down suddenly or just got heavy. That tells us what to load on the truck before we make the 16-mile trip out. Beyond that, leave the winding bars where they are.