There should be a bushing in the lower gudgeon.
We lost ours in a yard mishap when the boat tipped back off its cradle and the rudder snapped.
We were able to bend the gudgeon back into alignment before installing a new (and much improved) rudder that was built by Phil's Foils.
For the past two years we have lived with the rattle. The bushing needs an inside diameter of 1 inch with the outside being about 1 1/16" to 1"1/8".
I have been unable to find a match. Medium-wall 1" copper pipe appears to match the dimensions, but I have only been able to find a source that will sell me 12 foot lengths, I need 2 inches.
Last summer we sailed 2400 miles on the Down East Circle without the bushing with no problems. At night we have to lock the rudder over against one of the stops to prevent current or simple movement from producing an annoying rattle.
I would not let this stop you from purchasing a 30-2, they are a fantastic boat.