I use a rod too
although, now that I know about the s-shaped tube, I will be more careful. I bought a 1/4" four foot steel rod at the hardware store for $1.89. I wrapped one end with a little duct tape to avoid damaging anything, and use it to free the centerboard through the cockpit access tube (don't forget to unscrew and remove the plastic gromment that surrounds the pendent line). However, one simple precaution has almost eliminated my sticking centerboared. While my boat was on the hard off-season, I experimented with how far up my board would retract without sticking. I marked the pendent line with indelible marker in one color at the point where the board sticks, and in another color at a point about a foot away as a warning marker. My board never stuck last season. The "indelible" warning mark fell victim to UV rays a couple of weeks ago, and I pulled the centerboard too high and it stuck for the first time in two years. When I re-marked the warning, I used a particularly garish shade of nail polish from my wife's stash.