By "cracked one of the long locking sections that holds it all together", do you mean a stringer? Are your stringers made of wood or aluminum? If it is aluminum, you should be able to order the part from your nearest zodiac dealer. You need to bring yours with you to show the dealer the exact profile of the stringer (there have been a few stringer profiles over the years, one slightly different from the other).
If the stringer is made of wood, you might still be able to order it from the zodiac dealer, or you could get a local millwork to mill you one out of oak, or better still (if you want at least 39 more years from it), purpleheart.
What is the condition of the thrust board? Is it still solidly glued to the fabric? The boat must have been stored in the off season in ideal environmental conditions (cool and not too dry) for the glue holding the thrust board and the transom to have held up for this long.