The most common mistake we see on doors from this build era is someone trying to replace a torsion spring themselves. These springs hold real tension, and on a door original to a 1990s house, the winding cones and end bearing plates have often corroded or worn enough that they don't behave the way a fresh part would. That's not a job for a ladder and a wrench.
A second one: ignoring a door that's started drifting off-track because it still closes. On an older door, a bent track usually means the rollers are wearing unevenly, and left alone it eventually jumps the track fully, sometimes while someone's underneath it.
And the honest limitation - if the fault turns out to be structural, a warped panel or a frame that's shifted with the foundation, that's outside what a service call fixes. We'll tell you when the right next step is a new door rather than another repair, even if that's not the answer you called for.