imperialscum said:
The film went two times over schedule and two times over budget. I think in film business, that is pretty much the most obvious evidence of producer’s incompetence you can get. Even big studies freak out at even one of those conditions, let alone a newly founded independent studio. Even though this is widely-known information, for reliable source you can refer to Making of ESB by Rinzler.

I’m looking for a citation of your original claim here, and I can’t see it. Saying that the film went over schedule and over budget is one thing. It’s an enormous conjectural leap to suggest that Kurtz was fired during production as a result.