@dundee said:
The information you gave me is very interesting and it solved my problem!
This is very good. There are other things.
First, visit Window/Model Info (often!). Click File to see how big your model is. Click Statistics, then "Purge Unused". Back to File and you'll see that your model is 75% smaller. This is a good thing.
I tried my VisMap plugin to get an idea of what was going on in your original .skp. It showed a blank window where the VisMap should have been. On digging, I found that your .skp had some odd internal damage. Your "rev1" .skp had no such problem and VisMapped without trouble.
Internal damage was a common problem for me as I learned to SketchUp. How to avoid it? 1) Never make a mistake and never change your mind as you model. OK?
Now on to practical advice that a human being might follow. 2) Build sub-assemblies in separate files. (Small collections of geometry are seldom broken.) If you think it through in advance, you'll be able to File/Import and click the Origin inference, to correctly assemble the finished model. (File/Import automatically makes the import a component, same name as the file name).
And make your sub-assemblies just as you would do the cabinet making. That way you'll have a good magazine article, as well as a model.