'53 Merc vacuum wiper switch

[Eddie Morgan]

Is anyone here familiar with the vacuum wiper/washer switch on 1953 Mercurys? My wipers work just fine, but when I push the washer button, I hear a slight hissing sound coming from the switch.
My question is this: Is this normal, maybe to break the vacuum to the pump for fluid, or do I have a problem? As it stands, my windshield washer doesn't work. I have NOS assembly I installed and I'm not sure where to go from here. My hope is to keep everything original, as much as possible.