There on the right, the woofer rotate unit, according to the Leslie Organ Speaker diagram. One of crew members of the Curtis Salgado Band told me it's called the bass rotor. I read online that the woofer is the bass speaker. So glad I got a photo that shows the spinning; I thought it was vibrating with sound when I first looked at it, then when the sound lessened, it slowed, and I could tell it was actually spinning. I thought whatever was spinning was covered with very thin foam rubber. Before the show ended, I believed the covering was some sort of gray cloth. When it spun, the speed caused the blur you see in the photograph which must have influenced my perception, making me think it was thin, gray foam.
Here's a wide shot, taken from my seat in the booth beside the stage. On the left is the side of that vintage Samsonite suitcase with the duct-taped handle. I took this photo during the intermission between sets--the extra light allows you to see the cloth better.