There's a short list of things worth doing on your own: wiping down and lubricating tracks and rollers once or twice a year, checking that the bottom weatherseal still seals against the slab, and testing the auto-reverse safety feature by setting a piece of wood under the door and running it down. What you should not do, on a door from this era especially, is touch the torsion spring. These springs store enough tension to break bones or worse, and the winding bars and clamping tools to do it safely aren't something most homeowners own or have practiced with. Replacing a cable or realigning a track that's badly out of plumb falls in the same category - doable with the right tools, dangerous without them. If the fix is a worn roller or a loose hinge screw, go ahead. If it's anything involving the spring, the cable drums, or the door coming off its track entirely, that's a call, not a weekend project. More on what we cover across the area is on our East Haven garage doors page, and general service details are on the New Haven repair page.