On a door this age, the torsion spring is usually the first big failure - most were wound to last around 10,000 cycles, and a door opened twice a day gets there faster than people expect. When it snaps, the door either won't budge or drops hard and fast, which is dangerous if anyone's underneath.
The second common call is the opener itself. Early-2000s chain-drive units develop a specific rattle as the chain stretches, and the safety sensors near the floor get knocked out of alignment by a stray bike or a snow shovel leaned against the track - an easy fix that many owners try to diagnose as something bigger.
Our climate band here is cold and moderate, which isn't the harsh freeze-thaw cycling of the mountains, but it's enough that steel track brackets loosen over a winter of temperature swings, and rollers dry out and start grinding. None of this is dramatic. It's wear, on schedule, for a door of this exact age.