Simplify3D User Forum

I modeled a part using sketchup web. I'm not experienced so I eventually fumbled my way through.
I have a small dome with 3 components connected to it. First print left some space at the connections and the parts fell off.
I eventually figured out how to make sure the parts were solids and then used the union tool to make it one complete part. Was better, but not perfect.
2 Questions...

1. Is there a way to tell simplify to make just those areas have a higher res or something so the connections are better?
2. My last drawing edit has the longer top part showing up great, but when I do a print preview, that part disappears?

I'll attach the part and some screen shots
(I dont have simplify on work pc so I can not post a screen shot)

I've had issues with .STL files from Sketchup. They look OK, but they don't slice well. I'm not sure if some of the "repair" programs available will help or not.

https://all3dp.com/2/stl-repair-fixer-t ... e-offline/

Have a read of this thread:

viewtopic.php?f=9&t=3096&p=13400&hilit= ... ted#p13400

It explains a super simple way of sorting out issues where multiple parts are put together in some 3D packages.

Thanks guys.
I ran the model through some of the online repair apps and its good now.