Dave, welcome to the forum and congratulations on your new Oasis!
On the '05, you should have the rudder, stainless rudder pin (attaches rudder to rudder mount), rudder mount (stainless shaft with a 'T' top) and a horizontal plastic rudder pin (with keeper rings on either side) that secures the mount to the boat. Are any of these components bent or are the mounting holes sitting crooked?
Here's a link to Hobie product support. Further down the page you will find "
Original Hobie Mirage Rudder Installation Video" which breaks out the parts and assembly for clarification.