What Changes With the Season
Redondo Beach sits in a mild temperate band, so you're not dealing with the freeze-thaw swings that crack driveways and shrink metal brackets in colder parts of the country. That's the good news. The less obvious news is that mild weather doesn't mean no movement - it just means the movement is slower and easier to ignore. A sensor bracket here doesn't get yanked out of true by a hard freeze in January. It creeps, a hair at a time, from sun exposure on the bracket side of the door, from routine vibration every time the door cycles, and from small shifts in the slab underneath it. Because there's no dramatic seasonal event to blame, a lot of owners don't think to check alignment until the door starts reversing on its own. In a harsher climate the cause would be obvious. Here it isn't, which is exactly why it gets missed.
What Is Going On
When a sensor is out of alignment, the door won't close, or it closes and immediately reverses, and the opener's light usually blinks a pattern to tell you. The two sensors have to be looking at each other in a dead straight line, a few inches off the floor. If one bracket has crept even a little - from slab settling, from a bump, from a loose screw that's been loose for years - the beam clips the edge of the other sensor's lens instead of hitting it square, and the door reads that as an obstruction. On an older house, the fix is sometimes as simple as loosening the wing nuts and nudging the bracket back to level. Sometimes the bracket itself is bent or the mounting hole in the old wood jamb has worn oblong from decades of tiny shifts, and in that case realignment won't hold - the bracket needs a new, solid mounting point before it'll stay put.
When to Get Help
If the sensors have a light haze or a cobweb across the lens, clean them first - that's a five-minute fix, not a service call. If they're clean, aimed at each other, and the door still won't close, or it closes and reverses every time, that's a job worth having looked at rather than guessed at from a ladder. We don't recommend forcing a misaligned bracket back into place with pliers on an older wood jamb - on houses from the early 1960s, the wood around that mounting hole is often soft enough that forcing it just enlarges the hole further and the bracket won't hold the next time someone brushes past it. That's one we'd rather remount properly than patch twice. If your door is reversing and you can't tell whether it's the sensors, the track, or something else, call before you keep running the opener against it - repeated reversals put wear on the opener's gears that has nothing to do with the sensors themselves.
