Walk the door through a full open and close cycle while you watch the rail and the floor. Do this with the door empty and the path clear. The changes that matter are usually small, and they show up as a pattern across several trips rather than in a single trip.
What to watch on each trip
Look for a door that stops partway and waits before it continues. Listen for grinding or chatter along the rail, a rattle at the motor housing, or a change in pitch as the carriage moves. Notice whether the door opens more slowly than it did before, and whether it closes with a hard jolt at the end of travel. A remote whose range seems to shrink, or a status light that flashes without a clear reason, is also worth writing down.
Check the drive and the hardware
On a chain or belt drive, look for slack that changes as the carriage moves. Check that the mounting brackets are tight and that the rail is not bowed. A door that sits out of level or sags at one edge can add strain to the opener even when the opener itself is sound.
Test the auto-reverse
Follow the test described in the opener manual, which usually uses a board laid flat on the floor in the door's path. The door should reverse when it meets the board. Record the result. If the door fails to reverse, stop using it in automatic mode and arrange for service before you rely on it again.
Leave the springs to a trained technician
Torsion and extension springs carry high tension even when the door looks still. Do not adjust, wind, or remove springs yourself. Write down any spring noise or visible gap in the coil and hand that observation to the technician who comes out.
What to log
Keep a short note with the observation, the day you saw it, and the door's condition at the time. A reliable log tells the next person exactly what changed. It also gives you a clearer picture of how the system is ageing than memory will.
The age of the opener is a planning input, not a verdict. Once you know the install year, the garage door opener guide places the unit against its typical service life, and your log tells you whether the wear you see fits that picture.