When I got mine I had the same problem , sust out in the end that the switches had been put on the wrong way round ie. I could switch on the rear squirter and it would stay on but the wiper would only do one wipe :lol: :lol:
swapped the switches over (and the little inserts with the pics on and everything works fine).. :dance:
Might be that someone has changed a broken switch for and squirter rather than a wipe :-k