Animation model displays incorrectly?

I finally solved my problem with finding the right format for downloading commercial models from sites like SketchFab. The answer for me was only buying models that are available in the GLB format;

Unfortunately, although a lot closer to success, I am still not completely successful yet.

Here is a side-by-side display of the Piccolo Spider Robot I got from SketchFab. On the left you can see how the animation model is supposed to render/display. On the right you can see how it looks in my ThreeJS scene:

It looks like some of the parts of the model are not rendering or are transparent? My artist/graphics skills are not good enough to guess what is going wrong here (I’m a programmer, not an artist).

I really like this robot. The animations all work great so it’s just getting it to display right at this point If you were in my shoes, what would you do to try and fix this problem?

Here is a link to the model vendors page, so you can see a video of the robot.

Maybe the normals are flipped did you try checking the model in a 3d modeling app like blender?
if you do not have one you can try adding a double side for the material.