I had a similar situation back in 2011. I tried to get the dealer to register me so I could get the upgrade--he refused. Said I was the second owner and would have to buy the upgrade. You can read about that somewhat unfriendly exchange here:
http://www.hobiecat.com/forums/viewtopic.php?f=69&t=35587 When I contacted Hobie support, they corrected what the dealer said and immediately sent a new rudder. I also provide some tips for installing the new rudder. Jim Czarnowski, head engineer at Hobie, has an excellent installation video--again go to my link above.
I am sure Hobie will furnish you a new rudder; however, you will likely need to call or email their support, give them the serial number, and request the rudder.
Keith