V,

I got lucky with mine and it was swimming around on the inside of the UCX.  Could you be that lucky?

If you have the door that "fell out", it may go back in easily enough.  For me, I opened the UCX  and gained access to the adat optical jack.  So, I can't describe it well from here but....

Somehow, the back (or front?) "cover" of the optical jack "slid" off in a way....  This allowed me to "place" the door back where it came from (I think inside this cover) and the "placement" worked harmoniously with the spring inside.  Then I just slid the back (or front) cover on again and all was right with the world.   It snapped into place.

Really, I know that's a crummy description but.... you kind of have to think like the person who engineered it.  These have to be manufactured without too much trouble (tweezers and little human hands)....  So if you can get your mind around it that way, it may happen for you intuitively.

Indeed, the optical connector is useless without the door because the door helps hold in the adat cable.  Replacing the jack completely is not actually difficult (soldering) but there is the matter of procuring the same part and then removing the the broken one.

Hope this helps even a little.  Good luck.

Cheers,

Rob

PS.  This is the only problem that I have ever had with any of my RME gear (I've had 4 or 5).  Kind of silly and maybe not even RME's fault.  I mean, how would you go about finding one of these that is robust.  I think they are all kind of fragile.