I believe he said that he saw it on television.
Yes he did. "By US Senate G.Robert Blakey Committee on Assassinations," as he calls it. The HSCA hearings were televised. Those hearings were also recorded as transcripts and published as the first five volumes of the HSCA hearings and exhibits. So, where did anyone show CE573 and/or a picture thereof during those hearings? A couple of oldtimers have said that it wasn't shown during the hearings. I've searched, but I haven't been find anything in the hearings that indicates that they publicly showed it or a photo of it. I can't find it in the list of HSCA hearings exhibits either.