Graeme used his keyboard to write :
The problem, now cleared, was not the jets. No idea whether they're all the
same, but on this car, the water comes through a hole in the wiper spindle,
to be met with a cap which turns the water through 90 degrees, and directs it
through two jets. The blockage was within the cap, before the jets, and
whatever it was, was solid. Softened by running through the dishwasher, then
soaking for hours in a cup of hot water with washing powder. Much squirting
of contact cleaner (which may or may not have helped), poking with a tiny
screwdriver and old guitar strings and blasts from a compressed air aerosol.
Now working perfectly.

Thanks, yes probably the jelly like substance. It can be quite
difficult to clear out.