Yeah remove the wiper & the jet plastic tube, then try it & see if the water trickles out, also remove the rear door panel, take of the pipe & see if water comes out there, then you know its from that location onwards to the screen jet.
I tried it parked up and my 4 yr old son shouted "Dad, the car's bleeding...". Turned out to be a joint had popped out up inside the front wheel arch. Pain in the bottom since you have to remove the liner first.
Stopped working a few months again, and expected to have to do the same. This time I still checked the jets first, and they were blocked. 2 mins to fix this time, result.