It helps a lot - and thank you for the info!
I have since been able to remove it -- other than not knowing what I was doing, there was a problem in that the part the t-bar fits through was in backward, so the set crew never showed up! I'm thinking "that hole HAS to be there for some reason." I was able to get a vice grip on it and turn it, which loosened it up.... and then it just came out.
It seems obvious in retrospect that if it wasn't lined up with the hole, it hadn't been snugged down.
Anyway - got it apart, figured out the adjusting system after plenty of DOH!! moments. These things are really well designed and made. Like some Slingerland stuff I've worked on.
The reward: I love the way it feels with the single footboard. Very natural feeling.
Thanks very much for the guidance -- great group on this forum!