I want to swap the lock on my Multipla fuel cap to another one with an intact leather strap. Has anyone separated the the black 'Diesel' part to get at the lock? My finger is on a 'loose' circular ring so separation should be possible from one or both sides.
I dont want to try forcing it off as FIAT plastic is very brittle

I can answer my own question. I had hoped to swap 2 locks because one of the leather straps had broken. The method of swapping the straps is easy but it is too late for me as the second one broke
Swapping locks:
You prise off the rotating part on which I had my finger on and you can see 4 plastic clips You lever these off and can then swap the locks.
Swapping straps:
To remove the straps you push out two plastic 'pins' (see pics)
If anyone has a spare strap I would be pleased to receive it!