On a house from the mid-1960s, the first thing we check isn't the obvious symptom - it's what's original. If the torsion spring, end bearings, and track brackets are all from the build year, we're not just replacing the one part that failed; we're looking at everything load-bearing around it, because 1965-era steel fatigues as a set, not one piece at a time.
We measure the spring's wire diameter and length against the door's actual weight rather than assuming the sticker on the spring (if there still is one) is accurate - on hardware this old, it often isn't. Cold-rated lubrication goes on the track and hinges as standard here, given the climate this area sits in, not as an upsell.
If the opener itself is original too, we'll say so plainly: a chain-drive unit from the 1960s-70s era usually isn't worth repairing piece by piece once the circuit board starts failing. Replacement makes more sense than chasing parts for a unit that old, and we'll tell you that instead of billing for a patch that won't hold.