Rebbe used to come home on Friday night.
Does the gemara indicate that Rebbe was not tangible (which seems to be the property of these “ghosts”? I’ll see if I can find anything on it.
an incident indisputably witnessened by two Gedolai Yisroel, when they were bachrim.
Are you referring to the story with R’ Yosef Chaim Sonnenfeld as a bochur and the banker who came back to give a check to the widow who used to pay to have kaddish said, and needed to marry off her daughter when she fell on hard times?
I believe in these as well, but they don’t seem to fit the same characteristics as the classic apparitions.