The honest limitation: if a door's springs, rollers, and opener are all original to a house built in the early 1990s, maintenance can extend the life of that hardware, but it can't make 30-year-old steel torsion springs behave like new ones. We'll tighten, lubricate, and adjust everything we can, but if a spring is visibly stretched or the drums show wear grooves, we're going to tell you it needs replacing rather than servicing - patching a spring that's near the end of its cycle count is how you end up with a snapped spring and a door stuck down. On double doors especially, we check both springs even if only one shows symptoms, since they wear at close to the same rate and replacing one without the other just moves the next call a few months down the road.