Various restoration proposals were made in the twentieth century, but none were undertaken. When the town of Lüttich requested titular organist Pierre Thimus in 1986 to supervise a new restoration project, it turned out that all the pipework of the instrument had by that time disappeared. This fact, on the one hand lamentable, offered the opportunity to return the splendid Renaissance case to its original design and, by installing an appropriate instrument, to its former glory.
It was not long before the construction of a Renaissance organ in the spirit of the Niehoff school came to be seen as the best solution. This choice was unequivocally predetermined by the case design, and in particular by its limited depth, which almost dictates the customary arrangement of the stops of such organs on lower and upper chests. The project offered a unique opportunity to reconstruct in a historical case an organ of the flowering of the late Netherlands Renaissance, and so characteristic for Sweelinck.The instrument was built by Schumacher of Eupen. That such a style copy is in any way possible, is due to the fortunate circumstance that in the organ of St. Johanniskirche in Lüneburg an extensive and cohesive amount of Niehoff pipework survives. What is more, the principals and flutes have the same scaling as the Van Covelens pipewerk in the Pieterskerk in Leiden (the Netherlands). The two instruments make it possible to correctly reorganise incomplete ranks elsewhere and thus reconstruct scalings of flue stops with certainty. For the composition of the mixtures, those of the Rückpositiv in the former organ of the Nicolaikerk in Utrecht (Cornelis Gerritsz., 1547) were indicative, as well as certain written sources, such as a description of the former Niehoff organ in Zierikzee. There were insufficient points of reference, however, for the reconstruction of Niehoff reeds, and these were made after other examples.
In order to do more justice to north German repertoire, which sounds particularly well on this type of organ, the independent Pedal was better equipped than in the Niehoff tradition and an on/off device for the Hauptwerk coupler was added. Further adaptations serve mainly to facilitate later repertoire and liturgical usage. The Vox humana, moreover, can partially replace the Bärpfeife, for which there was no place in the Lüttich Rückpositiv. The Oberwerk Terzflöte can be used to imitate the Nachthorn (Cornett) 3' of late Niehoff organs. In dividing up further the Hauptwerk plenum, and thus reducing the Mixture, care was taken that the overall composition of the plenum was not altered.