The sound you're listening for is a rhythmic grinding or clicking as the door moves, getting louder near the top or bottom of travel where the curved part of the track is. That's a roller riding on a worn bearing or a flat spot on the wheel itself, and it's especially common on houses from Pittsburg's main building period in the early 1980s, where steel rollers on open bearings have had four decades to dry out without anyone ever lubricating them.
A second symptom is the door catching or hesitating at the same spot every single cycle - that's usually one bad roller hanging up in the track rather than a spring or opener problem, and it's worth telling us that detail when you call because it changes where we look first.
What it's not: if the door is slow on every part of the travel, evenly, that's more likely a spring losing tension than a roller issue, and we'll say so rather than sell you a roller job that won't fix it.