Leon is correct in that the 4 (left side) bugle rank members countermarched before they were supposed to. I just remember it was a yard line, so it could have been either 5 yds early or 10 yds early. This threw those 4 files so far out of sync with the other side of the band that there was absolutely no hope of recovery on the fly. As a sax player, I was up there close to the front where it happened and the first thing I saw was the Inf Band drum major countermarch early (complete with command whistle) and then 3 bugle rank members followed his lead....bugler #4 did not immediately make the wrong turn, but when he saw the others turn, he then double-timed it a few steps to catch up, not realizing that he was the one that was correct.
I'm pretty sure the tapes still exist in the band archives. When you watch them, pay close attention to the renegade drum major shortly before the early countermarch.
BTW, I thought the block "T" attempt at this point looked more like a backwards question mark.
Gary Thorpe, BQ '82