Hi Satoribomb - this is the other problem area in this model. There is one spot on the main body that has a darkened line along it. At first it looks like an edge:



But it isn't an edge - it is an area where the surface is folded in a slight zig-zag back on itself. Here I turned on control points for the surface and moved the 2 out of order ones slightly out of line with one another so you can see what I mean:



That kind of zig-zag fold in the middle of a surface is also going to generally hose operations that try to do surface/surface intersections like the booleans. There's the same thing on the opposite side as well.

If you have some of the earlier stages of this model saved off, you might go back and see if that zig-zag was in one of your original drawn curves or not - it's possible that it was created by some bug in a construct command, or it could also have been accidentally created by you when placing or moving points...

Unfortunately anything involving intersections is not very tolerant of these little perturbations.

Thanks for posting your .3dm file - that makes it much easier to see what is going on.

- Michael