I would be tempted to make a new one out of plastic card or even steel. Would be a good small and simple exercise in getting you into building things.
Just take the old one off, looks to be held in place with only a couple of screws. Cut off as little as you can get away with using a Razor Saw. Fabricate a new bit using the old one and bits to make a new one. Or you could perhaps re glue the broken bits back on with Plastic (liquid) Glue and put some Plastic card strengthening on the back. With a quick repaint I doubt anyone will ever notice.
I managed to destroy some of the Valve gear on my mallet and repaired it with some Ally Sheet cut thin and very small skews. Not only does it work fine, but no one has ever noticed the repair till pointed out.
With LGB possibly permanently demised, we will need to get used to repairing small damage such as this in the future. Good luck and post some pics of your handiwork when done. JonD
Have you tried Silvergate in the US? I requested a bunch of parts recently, including some pretty obscure ones, and they had all but one I asked about (including a new frame for my Spreewald). The prices were very reasonable as well.