Komori LS40 water damp and ink feed motors

Nikki denso NA70 series AC servo motors are used as dampening roller drives for our Komori LS40 press, I have changed 3 motors so far and the press is only 2 years old. Every time the rotor would catch rust and cause the motor to seize, today the ink feed motor wasn't starting, turns out its the same motor with a slightly different encoder, I will inspect it in a day or two but seems like the same has happened again, has anyone ever faced this kind of problem with these motors? is there anyway to avoid it?