Garage Door Roller Replacement: preparing for the visit

Since the cold snap the door has been stiff and noisy first thing, and after the last thaw the bottom corner began to judder. There is slush in the foot of the track and a bloom of rust on the lowest wheel.

Worth answering before the call

Are there two hinges stacked at the ends of each section, or one? Has the door ever come off its track or been hit by a vehicle? Is the track the two-inch residential size or a wider commercial track?

What is the difference between nylon and steel rollers?

Both are a wheel on a steel stem, commonly on ball bearings though standard nylon rollers can be bearingless; the bigger difference is the wheel material. A steel wheel is tough and suits very heavy or commercial doors, but steel on a steel track is loud and grows louder as bearings wear. A nylon wheel wraps a tire around the hub, absorbing vibration rather than passing it into the track, so the door runs more quietly and the wheel never rusts. For most residential doors, nylon is the usual recommendation.

I lubricated everything and the grinding came back. Why?

Lubricant restores bearings and hinges that are still sound; it has nothing to offer a wheel worn oval, a nylon tire that has cracked, or bearings whose balls have pitted their race. When a spray settles the noise for a day or two and it returns, the wear is in the roller itself and replacement is the answer. Spray on the track or a plastic wheel can make matters worse by collecting grit, so the technician cleans that off as part of the job.