yep,in amsterdam,I just put a strap around to make sure it didn't fall off till I got home then had a look.basically the locks are poor and cheap,but I took the three screws out on the inside gently take the cover off remembering where the spring sits then the black plastic bit that will probably fall out is the bit your interested in,on mine it just appeared to sit in a bowl with a little grease,with the bit on the end like a half circle with a wedge that goes behind the catch to stop in moving back when the lock is engaged.I think mine had vibrated out of its seat so wouldn't turn,so I sat it back in and gently reassembled it,it took me a couple of tries as it a bit tricky getting the barrel and spring to stay in place,but once all together mines working fine again,I've just reread this and its seems a bit complicated but it isn't really just remember where the spring sat and its simple,hope that helps.
