Torsion springs store enough force to break fingers or worse, and that doesn't change because the house is older or newer. On a 1964-era door specifically, the added wrinkle is that the winding cones, bars, and mounting hardware may not match anything you'd buy off a shelf today, so even the tools for a safe DIY wind-down can be the wrong fit.
We're not going to tell you every repair needs a truck. Simple things, lubricating hinges, tightening a loose roller bracket, checking the auto-reverse, are fine to do yourself. Springs aren't in that category. If you're pricing out a DIY kit for a house this age, factor in that you may be buying hardware sized for a system that's no longer standard, which costs more than it saves.