A new to me 80 Z28. The car didn't have the wiper hoses and I connected up the hoses and filled the tank. I primed the tube from the tank to the wiper motor. Still no squirt coming. Not sure how many years the wiper spay has been out of commission. They stripped most stuff off the underside of the hood...I suspect for the carb replacement. I believe pushing the wiper button in is what triggers the wiper spray. If I'm not getting any action, what is the most probable cause? The switch, the pump or other?