I've been thinking, and today I thought of something while getting pelted with lumberjacks and torn to bits by carronades. A mallet can't save a balloon under constant fire from a weapon under constant fire from a weapon specifically designed to attack that part. If you want to escape, you either need your pilot to out maneuver the enemy or wait for the enemy to make a mistake. No amount of good engineering can help you in any way, aside from prolonging your death. You are fated to be glued to your balloon until you go down.
So I suggest bumping up the mallet repair power from 250 to 300. No other changes. I haven't thought about this too in depth, but I can't immediately see any game breaking possibilities. Now two Heavy Carro shots can't break a balloon if you can repair it between shots or directly after you rebuild it.
Just tossing ideas around, wondering what you guys think