Springs are the line you don't cross yourself. A torsion spring on a standard door is under enough tension to break a wrist or worse if it lets go while you're working on it, and on a door this age the spring is more likely to be near end of life than a newer one. Bulbs, sensor alignment, tightening loose bolts on the track - fine, do those yourself.
What's not worth DIY-ing on a house from the early '90s is anything involving the spring, the cable, or the drum, because you're working on hardware that's already fatigued and you often can't tell how close it is to failing just by looking at it. If the door is heavy to lift by hand with the opener disconnected, that's your sign the spring is doing less than it should - call someone, don't adjust it yourself.