Joe Jr. cleaning

I’m prepping my Joe Jr. for use after a long winter of sitting. Forgive me if it’s blatantly obvious, but I don’t know how to identify mold in this case so, I’m wondering if what I’m seeing is just soot or something more serious?
I plan to do a burn off either way since it sat for months but, I’d like to know for future reference.

As you can probably tell, my Joe Jr. is relatively new. I only used it a few times at the end of last summer and then winter came so, I covered it and stored it in my garage.

Thanks for any help identifying the black marks on the insert and overall look of everything else. I’d appreciate any tips anyone can share regarding maintenance. I know the big one is to cook in it regularly but that wasn’t an option this winter so, hoping to use it with more regularity moving forward.