What you did explain makes perfect sense. I thought there are some kind of motor or solenoid which pops washer up from bumber but pressure makes more sense. That's what I meant with that dummy jet comment...
Where i am not clear on things though is how the jets are operated. Are they operated when washing windscreen with lights on? or do they have a separate different switch purely for headlight washers?
Have you not ever used yours before?
My headlamp washers do operate simultaneously every time I use windscreen washer. There are no separate switch for them and I cannot prevent headlamp washers operating even if I would like to.
I will look into wiring issue again but not sure if I have time soon... Thanks for your link I will look into it and try to locate that controller connector!