Pipe organs contain parts that wear out or otherwise become unserviceable. When an instrument reaches this state, it is obvious in some cases that there were errors in selection that may be capable of remediation.

At the time of replacement of the worn-out parts, the cost of altering other components will be at a minimum. Some of the principles used are discussed in the report of the restoration of the organ in St. Brigid's Roman Catholic Church, Red Hill.