The Problem
Your garage door safety sensors are the two small eyes low on each side of the track
Usually about six inches off the slab. They're supposed to stay aimed at each other in a dead-straight line. When one drifts even a few degrees, the door starts reversing for no reason, or refuses to close at all, and most people assume the opener itself is failing.
In West Allis that drift problem shows up more than you'd expect
And the reason traces back to the housing stock. Homes here were mostly built between 1938 and 2000, with the bulk of the stock dating to the 1960s and 70s across the named areas in this part of the county. That generation of garage was framed and finished long before sensor brackets were part of the original build - they got added later, often screwed into whatever wood or masonry was handy rather than into a dedicated mounting point. Forty-plus years on, that wood has moved, that masonry has settled, and the bracket has gone with it.
The sensors themselves rarely fail
What fails is the thing they're bolted to."
Where People Go Wrong
The usual move is to grab the sensor, tilt it by eye until the light stops blinking, and call it fixed. That works for a week, sometimes a month, and then it's back to blinking because the bracket under it is still loose or still shifting. Re-aiming the sensor without checking what it's screwed into is the single most common mistake we see on service calls in this area.
The second mistake is blaming the opener logic board. Homeowners swap the whole opener, or pay to have it swapped, and the new unit has the exact same problem within a season because the new sensors go right back onto the same compromised bracket.
The third is ignoring the wiring. Older West Allis garages, especially the ones with additions or opener upgrades bolted on after the original 1960s-70s build, often have sensor wire run loose along the slab or stapled to baseboard that's since been replaced. Foot traffic, stored bikes, a shop-vac cord pulled across the floor - any of it can tug a sensor fractionally out of true, and the fix people reach for is aim, not anchor.
We'd rather see the bracket replaced with a solid mount the first time than keep re-aiming a sensor that's fighting a moving base."
What Local Conditions Do
This area sits in a cold-severe climate band, and that matters more for sensor alignment than most homeowners realize. The slab a garage sits on doesn't stay still through a Wisconsin winter. Frost heave pushes concrete up at the edges as the ground below it freezes and expands, then lets it settle back down unevenly as it thaws. A slab that moves a fraction of an inch at the perimeter is enough to tilt a sensor bracket mounted to the jamb beside it.
On the older end of the local housing stock - the 1938 to 2000 range, with plenty of houses from the 1976 median build year still standing on their original foundations - that freeze-thaw cycle has had decades to work on brackets that were already an afterthought installation. Newer homes with poured foundations to current code handle it better, but they're the minority here.
Humidity swings do a smaller version of the same thing to wood-framed openings: swelling the jamb in spring, shrinking it in a dry cold snap, and taking the sensor's aim with it either way. None of this is damage you can see. It shows up only as a sensor that worked fine in October and won't hold a line by January."
What Changes With the Season
Early winter is when we get the most sensor calls
Right as the first hard freeze sets up and the slab starts its yearly shift. If your door reversed on its own or wouldn't close through November or December, that timing isn't a coincidence - it's the ground moving under the frame.
Midwinter tends to be quieter once everything has settled into its cold-weather position
Even if that position is slightly off from where it sat in summer. Spring thaw brings a second wave as the ground gives back the heave and the bracket shifts again, sometimes back toward true, sometimes further off.
We can't fix the ground
And we won't pretend a tighter screw solves a foundation that's moving a quarter inch a year - if a slab has settled enough that the bracket keeps failing no matter what it's mounted to, that's a foundation conversation, not a garage door one. What we can do is move the bracket off the compromised surface, onto the track itself or a mount that isn't tied to the slab edge, so the sensors hold their line regardless of what the concrete does underneath."
