A delivery truck sits backed up to bay three with its engine idling, and the roll-up door in front of it will not budge past the first foot of travel. Your driver is on the dock radioing that he's got a full pallet jack and nowhere to put it.

A commercial bay door rarely goes from fine to frozen overnight. Long before a loading dock door refuses to move at all, it tends to send a string of quieter signals first: a slightly longer travel time, a faint scrape partway through the cycle, an opener that seems to work a little harder than it did a few months ago.

A torsion spring rarely breaks without warning. It breaks without the warning being recognized, and those are two different problems.

By the time a house goes on the market, attention has gone to paint, light fixtures, and the front entry.

The technician pulls a bathroom scale out of the van, the same flat kind that lives in a hall closet, and slides it under the bottom section of your raised garage door.

That flat bang out of the garage is a sound you recognize the second time instantly.

Low afternoon light across a steel garage door turns every ripple in the skin into a shadow.

If your garage door opener still relies on a wall button and a couple of remote clickers, you may assume the only way to get app-based control is to replace the whole unit.

For years, the paint on the header above your garage door ran right up to the edge of the steel bracket bolted in the middle of it.

You press the button on your way to the car and turn back to watch the door come down.

One bottom corner is still sitting on the concrete while the other has climbed a foot into the opening.

The thermometer on the workbench shelf read 96 one afternoon. A front came through overnight, and by morning it read 58. A few days later you back out, and the door hesitates on the way up, scrapes along the left track, and lands harder than it used to.

You press the wall button, the motor hums, and the door lifts maybe four inches before it stops cold and settles back with a flat thud against the concrete.

The door on a detached shop usually got built tall on purpose. A fifth-wheel with the air conditioner on the roof, a boat on a trailer that clears the header by inches.

The change is small enough that you keep talking yourself out of it. In the spring you could hit the remote from the end of the block, and the opening was clear by the time the car reached the apron.

Stand inside the garage with the door closed and look up toward the back wall.

A car is trapped inside, and the opener will not run. Someone reaches for the red cord hanging from the rail, because that is what the cord is for, and pulls it without a second thought.

The door went down last night without a hint of trouble. Smooth run, clean landing on the concrete, motor shutting off right on schedule.

A technician looking at a door that has been run for a week on a broken spring can usually read the whole story off the hardware: a cable wound over itself at the drum, a rounded gear tooth still meshing but barely, a panel creased where the opener arm pulls hardest.

Balance is a physics word before it is a garage door word. On a sectional door, it describes a state of equilibrium: the springs above the opening store exactly enough energy to cancel the weight of the panels hanging below at every point in the travel, so the door has no strong preference for where it sits.