rescaling/repairing Sketchup files when making into STL

2 things:
Have you run the stl through Netfab to fix?
Have you tried sketchup plugin call Solid inspector?

post your sketchup file and I will give it try

Wow, you have a lot of work ahead of you. I threw together a pdf to better explain. http://www.12voltleds4u.com/Custom_Switch/Document1.pdf
Some will be easy to fix, others not so much.  What version are you using of skecthup?

wow so the designer didnt even merge groups much less finish details made. surprised I was able to even get poor print out of it after netfab. I have even removed wheels etc on some trying to make printing easier. thanks for the pdf info thats kinda what a netfab tech said about another stl file of a boat I sent him only he also said explode then make each groups parameters thicker and re-assemble. if that makes since. I have learned how to double click my way into skp files and manipulate them even reverse some groups assembled wrong and un-hide parts that never got deleted leaving ghost items trying to slice and print. seems lots are not as good at sketchup as they think uploading to 3D warehouse. some high detailed files almost need complete rebuild from scratch only having some parts to redo and use. some may be a way of leaving an ID behind but most are just errors.
at N scale size many of the details wont even be noticed if there or not. cool having interiors and engines etc for leaving hoods etc open though

still learning how edit features work in not only sketchup but half dozen other programs too like design123 apps and other cad types, as most have almost no instructions saying what a button does or how its used.