From the middle of the eighteenth century the castle was gradually dismantled. In October 1770 the organ was moved on the orders of Frederic II. of Prussia to the Martinikirche in Halberstadt, where Michael Praetorius had been organist a century earlier. The organ builder Johann Christoph Wiedemann was commissioned to move the organ. Nine new steps were installed in the instrument as well as a glockenspiel, two drum players and some decorative elements such as the “ears” situated on either side of the main case.
The new organ took the place of one built by David Beck around 1590, sold to Derenburg, where part of the case may still be seen, though considerably romantic transformed by Ladegast in the nineteenth century. At Gröningen the absence of the organ was a death-blow to the fame of the artistic ensemble and from then on the dispersal of individual items became ineluctable. In 1792 the wine barrel was transported to Halberstadt as well as an entry portal to the armoury of Dike Heinrich Julius. These two unique items were conveyed to a hunting pavilion, the property of Ernst Ludwig Spiegel, where they still be seen today. The whole castle-complex in Gröningen was demolished in 1817 - with the exception of one basement vault and some bricks - and it remained no more than an engraving and some drawers.
After the re-installation in Halberstadt the organ underwent significant modifications. In 1837 the organ builder Johann Friedrich Schulze intervened. David Beck’s organ gave away for a new construction at this time. In this instrument of a new design and a probably more Romantic colour, the Rückpositiv had no place and no doubt interfered with arrangements for musical performance in the tribune. Confronted with the rare beauty of the decoration the organ builders could not bring themselves to destroy it and so it was that this wonderful case came to serve as the decoration for a new instrument built by Schulze at Harsleben, a village situated a few kilometres from Halberstadt.