how do you take out that damn controller gun? if it had teeth, it would be armed to them, napalm doesn't do squat to it

Fire all your napalm at the controller and you will get a message saying that you should go pick up more napalm at the downed ship. Once you have done this you figure out that you have to set the icebergs on fire just before the controller starts feeding on them. Be warned, you only have a short time to do this and if you screw it up then you lose. Once the controller feeds on some napalm, the Ubermacht and the Greiffenhorst will separate.

thank you, you are a legend, i'm going to go and try it right now, thanks mate

Shooting all the napalm into the gun only helps you for a new pickup - you can shoot the ice any time.