How do you remove car wax from plastic parts?

I want to clean up some parts of my 74 Charger.
Previous owner did a great job at getting what appears to be wax in the plastic parts of the louvered window covers. Its the interior parts so I don't really know what it is.
Anyone know how to lift this substance out safely? I just tried a soapy bath and toothbrush scrub with Dawn dishwashing detergent and the attached pic is the results of that effort.
Thanks for the tips!

I'm betting the plastic is self destructing. I'd pull them off and repaint them. Gene

Pencil erasure or Maguires Back to Black

So the wife walks by; snapping chewing gum and says, "Whatcha doin'?"
I said, "Asking the pro's on Moparts how to clean this crap out of the plastic."
She said, "Why don'tcha use toothpaste like you do on my diamond ring?" and arrogantly walks off.
I think - what the heck, why not try it??!!
Viola!! Looks like it will work!!

Once you get it out, let it sit without putting any dressings on it to see if it comes back. That should tell you if the plastic is deeply contaminated or not. If it was just on the surface, I would use a product called "solution finish". It's a product like back to black, but lasts longer. That or spray paint it.

Try kerosene and a small brass wire brush

Toothpaste is getting it there! $0 spent, just elbow grease.

Looks great ! And no cavitys !!!

Top it off with transmission fluid, as seen on utube.

https://www.youtube.com/watch?v=d8ZfXzqF-3Y&t=1s

Wow! Who would have thought!? Thanks!

the toothpaste is just a very mild abrasive. I would definitely put something on after though, to protect the freshly exposed plastic

I'm not a fan of Back to Black. Very temporary solution and I don't think it removes the wax, it just hides it. I'm going to try some of the other solutions listed.