Hi,
I’ve taken a picture of the supposed mechanism that’s linked to holding the door at a desired position.

Is something missing?

 

the door

 

Unfortunately, your door check arm broke and the metal it was bolted into got ripped out. It's a relatively common issue. Good news is that you can get a new check arm on ebay for around $50. You'll need to straighten out the metal in the door and then use wide washers in order to distribute the load on the faulty metal. Yours is so buggered that I recommend installing thin steel plate on each side instead of washers. When mine was broken I just took the piece out altogether for a couple of years before fixing it. So if you're short on time, you can just do that.
I believe there was previously a write up with pictures on this subject, so if check the stickies. If you have any more questions, ask away.

 

Ah, found the write up: https://www.jaguarforums.com/forum/x...art-how-36075/