I once heard Lewandowski tell a story in an interview about being with Trump in the Trump corporate helicopter when he found out Manafort was a scumbag. IIRC, Trump exclaimed - paraphrased - ‘I have a crook running the campaign?’. He had the pilot go down to cell phone range and Trump called Manafort in an expletive filled rant. Manafort was shortly fired. I can’t find a full accounting of that episode.