Nrv turned up today but when I fitted it didn’t work.
Looks like the pressure is too low to open it?
Stripped out all pipework and discovered a hole in a pipe which had been rubbing on the wiper mech!!
Popped down local car place and got an inline nrv and used it to join pipes where section with the hole was cut out.. all back together and squirty things working a treat!!!
Looks like not all nrv’s may be the same pressure? Modern cars probably have stronger pumps!