l322 td6 fuel pressure regulator valve?

hi all,
yesterday evening just after getting into my 02 l322 fuel injection inact came up on the display and it started running rough.

I pluged in my faultmate this'avo and the engine ecu is showing three faults, Ones a glowplug realy.
ones "fuel rail pressure regulator-regulator valve jammed"
and "pressure regulator valve-output stage failure"

When I reset them it will run fine for 10-15 seconds and then injection inact comes up on display and it runs rough again.
I removed the pressure switch in the end of the fuel rail and it had some brown silt around the hole in the end of the threaded part, ive soaked it with wd-40 and left it up turned in the workshop in the vague hope it might cure it.

Is this a known fault on td6's?

Is there anything else I should be checking before spending 130+vat on a new switch if the wd-40 doesnt work?

thanks all, mick.

I would be worried about the brown silt, if it's in the pressure regulator, it's in the fuel rail and presumably in the injectors, at the very least I would change the fuel filter.

how are the injector leak backs? if the injector has gone open circut internaly it can cause the pressure sensor fault.
how often do you change the fuel filter?
is it hard to start?