Repair or replace a water pressure regulating valve?
Many water regulators are dirty or need a rebuild kit.
Cleaning the regulator inlets and orifices may fix things.
A rebuild kit may be needed.
normally the diaphragm is the component that usually fails most kits come with a new spring and diaphragm.
some as cheap as  $15.00 for just the diaphragm.
Kits that have the entire internal setup spring, diaphragm, valve, screen, o rings, screws. Can cost over 100$.
So I suggest trying to clean them first.