Black material in the track is a clue, not a diagnosis. It may be compacted household dirt, deteriorating weatherstrip, rubber or polymer from a wheel, coating worn from hardware, or a mixture of several materials.
Clean a small area and observe where fresh debris returns. Material concentrated along the wheel path, combined with bumps or wobble, points toward roller wear. Fibrous material near the jamb or interlock may come from pile weatherstripping. Metallic sparkle or scoring deserves prompt inspection.
Do not assume that spraying lubricant will dissolve the problem. It can turn loose residue into an abrasive paste. Collect a clear photo and note the door’s sound and movement.
Is black dust proof the rollers are broken?
No, but it becomes more significant when paired with grinding, uneven travel, or visible wheel damage.
Request track and roller inspection using the form below.