Loading pressure regulator #65 on some of my k machines are very noisy during rinse. I have taken them apart and back together clean. Is the problem with the spring or the black rubber valve? I have seven of them and if it is a matter of replacing a component I would like to try it. Thanks. DDC.

Those pressure regulators are normally solid and have seen them last the life time of a machine. If your pressures are good and stable check with Fresenius for any recalls or such.