You need the pressure to force it out, so the WD-40 is good. Actually, when I did the same thing, I started with a good soap and water washing in the kitchen sink, and used an old toothbrush as well, and worked the hinges opena dn shut while holding the knife under the running tap. It not only got most of the sand out, but also got rid of the remnants from the salt water. Then, I went with the WD-40, and worked the hinges more, until I finally felt that most of the grit was out of the hinges when I opened and closed the blades/tools. Take your time, be patient, and you'll be fine.