 door strap broken
Hi guys, Firstly thanks to all that posted before me, I had the same problem on wifey's Cooper and took a look at the weekend based on your messages, my findings.......
The noise when something falls off is in fact a spring retainer and can be easily replaced without resorting to the purchase of a new assembly.
After removal of the unit, look at each side and you will see the assembly consists of two plastic 'balls' that locate in the strap to hold the door at each position, on ours the one ball was still functioning but due to the oposing 'ball' not under pressure the whole thing was useless.
You will notice the side that is working has a shiny plate holding the spring in position, on the other side the plate is missing, now take a look inside your door and you will find the missing plate, by pressing the spring in slightly you can slide the shiny plate back in and then to stop it happening again I added a drop of glue to both plates (just in case).
Jobs a goodun as they say
PS Just remembered 'Torx key (female)' mentioned earlier, I used a standard 8mm socket on an extension and it was fine.  | 
