I have a 79 Oday 23, which has the same centerboard setup as the 25. I've used the "rod down the tube" approach alot. When I first bought my boat, the centerboard seemed to stick in the slot frequently. I went to the hardware store and bought a three foot length of 1/4" rod. Take off the grommet that surrounds the pendent line in the cockpit; you'll see that the hole for the line is acutally quite large. Put the rod down the hole gently; some of the Oday's have flexible hose as part of the conduit. Once the end of the rod hits the edge of the centerboard, tap on the end of the rod. Sometimes, its taken only a light tap to dislodge the board; sometimes I had to give it a good whack. I think at one point, I made a cushion for the end of the rod out of duct tape so it wasn't sharp metal on fiberglass. After cleaning out the slot and replacing the pendent line and shackle, I haven't had the problem for a number of years.