I too had rust issues with my frame. Here's my thread. http://www.airforums.com/forums/f44/...ns-113780.html
. They can be repaired, all depends on how much work you are willing/ comfortable doing. For the rusted away section of main frame, I went to a local plumbing/ sheet metal shop and they were happy to bend it up for me. A little backyard welding and done. If you can't weld, you can usually find someone who can. The project does take up a little real estate around the house. My neighbours are finding it quite entertaining, especially the shell separation.