I’m hitting a similar issue in another topic. Pretty sure that he uploaded his STL version of the model, and those can have a lot of holes in them. They’re also all triangles, which SketchUp doesn’t need to be. If you download the STL version and import that into a new SketchUp file, with the model units set to meters, it hopefully won’t have any holes.
STL models seem to be insanely complex. I’m using CleanUp3 to try to make them more sane:
Looks ok here… I ran Edge Tools to close any edge gaps, then MakeFaces to close holes. Then CleanUp3 to remove and duplicate faces, etc. Still needed to hide a couple of stray edges manually. Kind of expected that some amount of clean up will be required with stuff from 3D Warehouse.