In principle, initially there is no mandatory retrofitting for machines that have been certified to the "old" MD, provided they have not undergone a significant change
in the context of the Product Safety Act (ProdSG) .
However, if it is actually the case that only the manufacturer's declaration is available for your machine, then it is always mandatory for this machine to undergo a conformity assessment procedure. The manufacturer's declaration says that it is partly completed machinery in the context of the MD, which the integrator is making into a complete machine.
From the operator's perspective, all machines are governed by the industrial safety regulations (BetrSichV). This requires a hazard assessment for all power-driven work equipment (machinery), so that its safety is analysed at regular intervals. If any safety defects are established, they need to be rectified.