 Complete the following phrase:  Under Hammerspachs successor, Hans von Zwingenburg, the well piping was replaced in 151012 and building damage repaired. But the next superintendents, Nikolaus Mathias and Peter von Rada, complained of serious shortcomings. In 1547 the castle-guard was taken over by Christian Schwärzel. The construction work started by him was continued, after an interruption, by his successor in 1560, Alexander Gabelowitsch né Sandri. During the 