I've just come across this thread, it looks to me like sensor corrosion and not dust.
I had a similar issue with both my Leica M9s and my Monochrome which also had a cracked sensor to top it all (see image below).
The give away is the dark spots surrounded by lighter circles, which is what seems to appear in your images as well.
It's noticeable in the bottom RH corner of your image #1.
I'm taking a wild guess here, maybe that's why Sony stopped making these sensors?
Send the camera back to Fuji, even if it's out of warranty, this is not normal. To their credit, Leica repaired all 3 cameras free of charge even though the warranty had expired some years prior.
Good luck & best,
Mike