I actually had this happen a few weeks ago. I floored the accelerator wide open on a two lane road and the kickdown popped off the transmission linkage and jammed against the header. It was jammed so tight the return spring couldn't pull it back. Fortunately, I had enough room and time to turn the switch off, slow down and pull off to the side of the road. It was a rather scary couple of seconds. Needless to say, I will probably be switching to the slider type linkage in the near future since I have one laying around (I think) even though I have fixed the "linkage popping off issue"