YWN –
I was personally at a bris this past summer where this story was told over. It was a very emotional time for all of us that knew Rebbe (Reb Shlomo) z”l, as this was the essence of Rebbe. If you truly knew Rebbe, you would understand that this story is 100% true, which is why there was not a dry eye in the room when the story was told over by the bris.
Amazing.