Most of the houses we get called to here went up around 1971, the midpoint of this suburb's building boom, and a lot of those original doors are still running their first set of rollers more than fifty years later. The telltale sign is a grinding or chattering sound right as the door starts moving, usually loudest a few feet off the floor where the roller rides over worn stretches of track. On older steel track from that build era, the roller wears unevenly because the track itself has sagged slightly from decades of use.
You might also notice the door catching or jumping at the same spot every time, or the opener straining harder than it used to on the first few seconds of travel. That's a worn roller binding in the track, not usually a motor problem, even though homeowners often assume the opener is dying first.