Maybe around 1985? Camped out at Doug Robinson's place in Round Valley. Dale had already built the plywood wall and had now set up a horizontal crack machine.
So he puts a tape (probably 8 track) in his panel truck and starts doing laps on this thing. It was like watching a ballet how he traversed that thing forever, back and forth and never touched the ground. When he came to one the end of the machine, he would cut loose his feet, rotate and do it again. And again. And again, ad naseum.
Wish we would have had digital then. It was truly impressive.