Suche Fachmann

I own a Seisenbacher brand cider press from Ybbsitz, built in 1956. Two years ago, there was an accident. The pressure relief valve extended. Since then, the piston pump has been generating too little or no pressure. Does anyone know anything about these piston pumps or understand how they work? Unfortunately, the company that took over from Seisenbacher destroyed all documentation relating to the cider presses ever manufactured.