A panel can have more than one roller assembly, and the condition of each matters. Discuss whether compatible assemblies need replacing together. Replacing only an obvious damaged wheel may leave an uneven panel if the other support is worn or cannot be adjusted correctly.
The wheel shape and diameter must suit the running rail. A visually similar wheel is not enough to establish compatibility. Ordering from an approximate photograph can leave the door unsupported or incorrectly aligned, so confirm the part information before committing to a replacement.
After fitting, the panel height needs checking against the opening and compatible hardware. Excessive adjustment is not a cure for an unsuitable part. The aim is supported travel and workable clearances, with any remaining frame or track limitation explained before handover.
Replace accessible compatible roller assemblies on an accepted panel, set the height and check ordinary travel and stops. Scope limits: Ordinary non-powered safely handled panels only. No heavy specialist lifting, glazing work, powered operators, structural changes or access-control integration.