Extension Springs, Aging Chain Drives
Doors installed from the late 1970s through the 1980s were more likely to ship with extension springs instead of torsion, and openers from that first wave of chain-drive units are long past any reasonable service life. If your house went up close to that 1979 mark, you're a strong candidate for an opener that's on its second or third remote and a spring system that was never upgraded when the door itself got replaced somewhere along the way.

