Ok, my first chance to give something back
It seems to be a very common problem, the ashtray mechanism fails and will not stay in.. rather than source a replacement i decided to try to repair it, because i'm tight like that
so here goes....
plenty of info on removing the whole assembly so i wont go into that..
1, remove the front cover, its hinged at the bottom and just pops off - be careful not to break the clips (as a bonus i found the coin holder hidden inside!) - also remove the ashtray liner...
2, remove the top cover, be careful when you come to refit this as one of the pins at the side kind of slides under the side cover... you'll get what i mean!
3, Release the spring and let it roll back
4, prise off the small yellow gear wheel - when you come to refit this put pressure on the it from underneath or you will dislodge the bit it attaches to and its a bit of a pain refitting it...
5, Remove the lever, you will need to pinch the two halves of the stud together underneath. when refitting note that there is a lip at the front that has to go inside the slot
6, now you can slide the drawer out to the rear - when refitting align the rails carefully and add a little grease to them to allow it to slide easier
7, you can now see the bit that is causing the issue, there should be a small offset V shaped piece of plastic but it breaks off... I cleaned the area of the remaining bits then made a small hole with a soldering iron.
I then made a very small V out of a bit if then metal and pushed it into the hole so it protruded below. after a bit of testing and adjusting using the lever to make sure it worked smoothly i applied some araldite underneath to secure it in place.
re-assembly is the just the reverse steps and hey presto - works like new