Berluto pressure reducing valves use a single, removable cartridge that can be easily removed, serviced and reinstalled.
This repair kit includes all the required seals plus a new diaphragm, allowing you to fully refurbish the valve assuming there is no other damage or wear.
In that case you would need a complete new cartridge set which also includes new seals and membrane.
Provided the valve can be made safe, the top cover can be removed while the body remains in place, giving direct access to the cartridge for maintenance.