Methods and apparatus for extending the reliability and usefulness of a fullwidth printhead by providing a redundant temporary replacement printhead module that can be positioned to compensate for missing or faulty jet nozzles. In order to take advantage of a single extra printhead module and to be able to compensate for more than a single failed nozzle, the replacement module is mounted on a separate translating x-axis and preferably provided with roll adjustment along another axis so that an effective spacing of nozzles in the replacement module can be adjusted to align with detected defective nozzles. The fullwidth printhead is formed from at least one array of smaller printhead modules. The arrays may be offset by a non-integer spacing interval of the individual nozzles. For example, if the nozzle spacing is S, the offset may be S/2. By virtue of the x-translation and roll capabilities, a single replacement module can accommodate replacement of one or several defective nozzles spaced closer together than the total length L of the replacement module, even if the defective nozzle(s) are located on different printhead modules and have a non-integer spacing.