Thank you for the suggestions people.
I took the advice from @JDS and removed the pipe and validated we had a squirter. Boy did it squirt.
I then struggled for the next 30 minutes pushing the pipe back on again. The pipe learnt some new swear words as 2.2l of water dribbled on my garage floor.
No dice when I eventually got 500ml of cold water in so went full send and boiled the kettle and stuck some warm water in.
We now have working jets and I diluted the less that boiling water with cool water. Must have been clagged up somewhere or an airblock.