Leaking Windshield Washer

I have a problem where one windshield washer runs water periodically on it's own. The truth is that I don't even know where in the boat to activate the three washers across the top of the windshield. It sounds stupid but true. Can anyone point me in the right direction?

The windshield wipers operate on our 73 53' Hatt at the bottom of the head riser at the lower helm. We have three "knobs" that point to down that operate the wipers. I believe they function for each windshield washer/fluid also.