Hi Chris, there seems to be 3 different problem areas. In the first area that I investigated, the problem seems to be that there are 2 surfaces stacked up right over top of the same surface area, that will prevent being able to get a proper closed solid:






Notice above when I selected the thin face in that area, that the display actually shows a kind of mix of selected and unselected colors bleeding through each other? That's an area where there are 2 surfaces overlapping right over top of each other with some of their outer edges joined, but then other edges unjoined. To get a solid you can't have stacked surfaces like this, so in this area the fix will be to delete those stacked surfaces and construct new replacement. It also looks like some of the surrounding surfaces may need to be untrimmed and retrimmed again as well because something is wrong with their boundary (note the sort of triangular hole there, that's a display mesh failure probably because the boundary is self intersecting or otherwise mangled in some way).

I'll see if I can tune up these areas for you, but if you want more information on the techniques for untrimming and retrimming there is an object repair tutorial here:
http://moi3d.com/forum/index.php?webtag=MOI&msg=446.17

- Michael