Well, you're starting by jumping into the deep end of the pool. The shaft(s) that have broken are the worm shafts and its usually caused by the drive coupler being out of alignment. You'll need two new worm shafts with the associated bearings, auto index alignment tools and a pick tester to get the gear lash to less than .001". I'd suggest getting Amada or an experienced independent tech. I've been working on Amadas for 30 years and this is one of the most frustrating jobs on them, especially since its on the lower turret.