If the door groans or jerks partway up, that's usually a spring losing tension, not the opener failing - on a house from this stretch of years, the spring is the first thing worth checking, especially if it's never been swapped. A door that drifts down a few inches after you close it is telling you the spring can no longer hold the door's weight, and that's not a lubrication problem, no matter how much WD-40 goes on it. Cables fraying at the bottom bracket show up as a slight tilt to one side when the door's moving, and on original hardware from the late 1980s, that fraying is common enough that we check it on almost every call out here. None of these are exclusive to any one house - they're what happens to steel and springs of that vintage over enough Texas summers.