As Remi says, use silicone.
When I raced an Equipe II XR in the old days, I used a silicone jell to spread on the gasket to facilitate easy movement of the dagger board (stays on longer than a spray). However, it looks like the Phantom may have a more serious problem. I could always move the daggerboard on the Equipe with my foot even without the silicone. The silicone just made it easier.