No need to soak down the whole wader if you know the general area of the pinhole. I just use a 500ml spray bottle
And Fishin' Hole, Cabela's etc carry Aquaseal
Turn the waders inside out. Then, go to a dark room like your bathroom and shine a flashlight from inside the legs of the waders. You will see all of the holes, instantly. Use a black marker to draw a small circle around any holes. Apply sealant to the inside of the waders. If the socks leak they will need to be replaced.