Welcome! You must have been doing some research before you decided to buy. Congrats on both machines. Both are at the very least uncommon to rare here in the states. As much as I want a 320 I would have passed on getting it with the conditions on shipping. They probably wanted to remove the responsibility of shipping it from themselves. If machines are not packed correctly they're easily damaged. I'd say in the neighborhood of 40 lbs (18 kilos) for shipping and there might be some oversize charges as well.
If it was me, I'd pack foam all around the machine including the bottom inside the base so it can't move inside the case and a layer of cardboard then foam sheets around the outside of the case too so nothing can move. The foam outside will help protect against punctures. Bubble wrap and packing peanuts aren't stable enough and will allow the machine to move. It's the movement that tears things apart. Picture a bunch of gorillas tossing the box around. That's the kind of treatment you need to expect from shipping companies here. Maybe things are better in NZ.
Manalto: I've heard of using kerosene but not mineral spirits. Have you tried mineral spirits? I've used it before on parts I've removed but not to flush out the inside of a machine. I have some here but would have to buy the kerosene.
I have a Brother that works fine at high speed but the blind stitch setting doesn't work well at lower speeds. I also haven't figured out how to take it apart to get to the cams inside. Brother built the machine with the stitch selector in the base of the pillar where it's hard to reach.
Rodney