Sources connected to "Idol" tell us there's some concern among the brass that Jackson is not well-suited for the mentor role, but they feel they need him because he's the glue that helps keep the show together.
As for his replacement, sources tell us Nicki Minaj's deal is 99 percent done, but still not a sure thing just yet.
We're told the honchos are keenly aware Mariah Carey isn't a fan of Minaj and doesn't want her at the table, a fact producers love because they think the conflict and tension will be good for the show.
And we now know "American Idol" will once again go with a fourth judge. Sources say producers are gunning for someone…