A host of AOing problems

Hello!

I am having some troubles AOing an object I made. I am getting black marks and lines around where I joined objects
with CTRL+J, I am having no luck with fixing it. I attached the BLEND file, so if someone could look at it and tell me what I’m doing wrong: that would be great! Have a nice day!


Attachments

cattlePanels.blend (648 KB)