The Apple Service Source Solution was so lacking I just had to share.

Can’t connect/disconnect MiniDock

Replace mechanical latch.

Luckily Trash80's solution is a little more complete. I tried to dig up what Apple had to say, but that's it... They go on to show replacing the latch but it looks like the Duo would have to be disconnected first. I've never played with a MiniDock before, just the full sized ones. At least it's amusing.