Gents,
Sorry to disillusion you, but it can't be brazed or soldered. It's pot metal.
You might try gluing it with JB-weld, or epoxy, and then a little hand paint over the glue. Few get that close to a grill star to see your handiwork, so it might work.
They are brittle and fragile. Tom Hanson, of the Classic Center and formerly Caliber Motors told me that they break so often they would stock them at Caliber.
Michael Salemi
1969 280SL
Signal Red 568G w/Black Leather (Restored)
President, International Stars Section
Mercedes-Benz Club of America