A door built around 1963 usually means one of two things by now: the original steel door has been swapped once already for something off a big-box shelf that doesn't quite match the opening, or it's still running the original hardware with decades of paint and patch jobs holding it together. Either way, the springs and cables on a house this age have almost always been replaced at least once, sometimes with parts sized for a different door. We see mismatched spring wire gauges more in older sections like this than in newer builds, because a past repair used whatever was on the truck that day instead of measuring the door correctly. The climate here is cold-moderate, not the deep-freeze conditions that crack springs from cold shock, but decades of temperature swings still fatigue steel over time, and a 60-year-old house has had a lot of those cycles. If your door is original to a house this age, the opener almost certainly isn't - most of those were replaced once the older chain-drive units wore out.