Nerang has a lot of long-serving doors that have never been formally inspected. They have been maintained the practical way — a squirt of lubricant when something squeaked, a nudge when something stuck — and they keep working, which is precisely the problem. Informal maintenance quietens symptoms without correcting causes.
A first service on a door like that typically produces a list: a dry roller, a loose track bracket, a few broken strands in a cable, a balance that has drifted, and an opener whose force setting has been increased at some point. None of those is dramatic on its own. Together they explain why the door has been getting steadily worse.