The knock will more than likely be the anti-rotation link on the front suspension. Renault couldn't find the fault on mine after two trips in. I took matters into my own hands and replaced it. It knocks no more!
It's true. It may be for sale shortly. I have a house to run now and thus need to look to the future.
I'll be sad to see it go, but it will bring someone else an excellent experience to own a rare model.