well the only damaged part of Gaia is that it has an opening at the cockpit...compared to the other 2 zakus it's damage is considered less..and the anime need not show u exactly that they are in the process of repairing Gaia to prove that it is repaired. The only Zakus available in Minerva is the red gunner and the blaze phantom..which both either lost their arms or worse in the previous battle against EA and ORB.