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ok do this.. while pressing in on the washer button, wiggle it up and down and side to side pretty hard (but not hard enough to break it)
do this for a minute or two
TADA! fixed for a week or two.
When it acts up again replace the multi-malfunction switch.
If for some reason it still refuses to work, unplug the connector at the washer pump (bottom of washer bottle) and hook up a test light or multimeter to the two leads. Observe to see if you're getting a light (or ~12v) when you push in the button.. if so.. bad pump.. if not.. something else.