I feel your pain
Sorry to hear about it. I am sitting with a Foss foam rudder on my garage floor waiting for the rest of the new hardware to come in. The same kind of thing happened to me, and I narrowed it down to a weakening of the lower gudgeon from corrosion when it gave way, the rudder split in half. I have not found another place to get the rudder except foss. Perhaps the Boat US people can point you to another supplier if there is one. I felt lucky to just be able to find a rudder, I was ready to do one from a solid wood door before I found out about Foss Foam. Come to think of it I could have done it and saved a few bucks and probably had one that wouldnt break. Good luck