Years went by.
And then Drew reviewed a product: Re.Mov.It, aka DSR-5. (Sorry Drew, I can't find the reference in your blog)...
I ordered some:
Holy cow! This stuff actually works!
OK, it doesn't actually dissolve the silicone (I don't think anything would do that). But what it does do is soften it and swell it, making it easy to scrape off.
I applied it using the end of a paper napkin, wiping it on the silicone over and over. And then I lowered my thumbnail and continued to wipe back and forth, scraping the silicone as well as wetting it. The silicone came right off!
I need to mention again that previously I had actually reached the point of damage to the naugahyde headliner in trying to remove the silicone... and now it's gone!
If you have a Previous Owner like ours, you need this stuff!