Garage Door Track Alignment Is a Measurement
Looks Right Is Not a Diagnosis
Track misalignment that causes real problems is usually a quarter of an inch or less. At that scale the human eye is useless and a level is not, which is why alignment belongs in the category of things you measure rather than assess. Four checks cover almost everything, and none of them needs specialist tools.
Check One: Are the Verticals Plumb
Hold a spirit level against the face of each vertical rail, front to back and side to side. Both rails should be plumb in both planes. A rail leaning inward pinches the rollers; one leaning outward lets them wander toward the open edge of the channel. This is the check most likely to find a loose bracket, because a bracket that has moved almost always shows up as a rail out of plumb before it shows up as anything else.
Check Two: Are the Rails the Same Distance Apart
Measure between the inside faces of the two vertical rails at the floor, at mid height and at the top of the vertical section. The three numbers should match. A rail that converges as it rises squeezes the door and produces a bind that gets worse the further the door travels. A rail that diverges lets a roller drop out at the top of the vertical run, which is one of the most common derailment points.
Check Three: Is the Gap From the Door Consistent
With the door closed, look at the space between the back of the door section and the rail at every roller position. It should be even top to bottom. A gap that opens at one end means the rail is not parallel to the door face, so the rollers are being asked to sit at slightly different depths as the door moves, and one of them will be taking a side load the whole time.
Check Four: Are the Horizontals Level and Equal
The horizontal sections should be level or very slightly sloped back toward the rear hangers, and both should sit at the same height. Measure from the ceiling to each rail at the front and at the rear hanger. Unequal heights twist the door as it flattens out, and that twist is transmitted straight into the hinges and the top section.
Why Small Numbers Matter
A roller is a small wheel in a shallow channel. The clearance between the wheel and the walls of that channel is measured in fractions of an inch to begin with. Take a quarter inch of that away with a rail that is slightly out and the wheel is running in permanent contact with one wall, which is why misalignment shows up first as noise and as one roller looking far more worn than the rest.
What to Do About What You Find
Bracket adjustment covers most of it, and on a residential door the vertical rails are typically slotted so a bracket can be loosened, the rail nudged and the bracket retightened. This is straightforward work with one important exception: never loosen anything while the door is up unless it is properly supported, and never touch the bottom brackets at all, since they are under cable tension. If the numbers are out because the opening itself has moved, adjusting the rails is a partial answer and the structure needs looking at.
What a Technician Should Tell You
After an alignment, ask for the measurements. A competent job leaves both rails plumb, the spacing equal within a small tolerance at three heights, and the horizontals level and matched. Those are numbers somebody can read back to you. If the answer is that it looks good now, the alignment has been judged rather than measured, and judgement is what let the door drift out of true in the first place.