We all know that when it comes to words describing tone, words can often be taken totally different then as to how it was intended. As "funeral" had stated, "motor drive". That is what I understand as well to simulate speaker breakup within the Axe. Mess around with that parameter and the MV to catch the just of tonal change.
Nothing really on the internet, (that I found) that specifically demonstrates audibly what it sounds like. I found one spot but you have to join the forum to hear the progressive sound bites of a V-30 heading towards breakup. Here's where I found how to listen to the clips. This is the forum you have to join to hear the clips.