Reprogramming a remote, replacing the battery in a backup unit, or swapping a worn wall button are all reasonable for a homeowner to handle without calling anyone. None of that touches the lift mechanism and none of it can hurt you if it's wrong.
Swapping the opener itself is a different job. It means setting travel limits and force settings correctly, which on an older door with worn springs can mask a spring problem instead of fixing it - the opener will struggle and burn out early, and the real issue, the spring, never gets addressed. On a 1961-era door with original hardware, there's also a decent chance the safety reversal sensors aren't wired in at all, and getting that right isn't a guess-and-check job. If your door is original to a house from that era and you've never had the springs serviced, that's worth a look before anyone installs a new opener on top of it - putting a new motor on bad springs just moves the failure point, it doesn't remove it.