Some of what breaks on a door this age is reasonable to handle yourself: lubricating rollers and hinges, tightening loose hardware, clearing debris from the track, replacing worn weatherstripping. None of that needs a call.
What doesn't belong in a DIY list is anything involving the torsion spring or the cables under tension. On doors from the late 1980s, those springs are usually original or close to it, wound tighter than people expect, and they don't fail gently. We also don't recommend homeowners open an opener's gearbox to chase a stripped gear - by the time it's stripped enough to matter, the unit is usually due for replacement anyway, not a $20 part. If the door won't move, is off its track, or the spring has visibly let go, that's a call, not a project.