String my friend....... String, a usefull adition to any tool kit........... stuffed into the rear bit with the vent's that keeps falling off when the pushchair hits it. String... that old friend.......... cut off the actuation arm from the wiper motor, the etch-a-sketch bit leave, then tie string onto the highest point on the nearest blade...and....bob's your uncle!! clear screen.... Tongue in cheek yes... But I have done this to an old Mk 3 cortina many moons ago, coming home from Devon on a stormy night!