A torsion spring is under enough stored tension to break a bone or worse, and on an older door where the winding cone may itself be original, we don't recommend touching it without the right bars and a clamp. What you can safely do yourself: check the track for visible gaps at the wall brackets, listen for a grinding roller, and note whether the door drifts down on its own when disconnected from the opener - that last one tells you the spring is going, and it's the detail worth having ready when you call. Past that, it's a repair job, not a weekend project, and we'd rather you call than end up with a cable across a hand.