Sometimes when I get into my rarely driven 88 K 1500, I push the thumb switch to clean the windshield and nothing happens. The first time I believed it was the washer pump until I tried turning on the wipers and they didnt work either. After a couple minutes they both kicked and worked normally. If I use it daily, they continue to work. If I let it sit a few weeks. They take time to kick in. This leads me to believe there isnt a loose connection. The switch I believe is mechanical/electrical meaning you physically lift up on the stem to activate the electric switch. How likely is it that the contact between the stem and the switch collects a lite layer of corrosion as it sits and after using it a couple of times the connection gets cleaned and contact is made? Continuous use keeps the corrosion away , enabling operation.