EDITED:
It is the thumb safety blocking the hammer strut. The grip safety is not installed. That's my mistake.
Fellas:
I thought I'd made every reassembly mistake possible with a 1911 forty years ago but just found a new one. I like new mistakes better than old ones, but this is a doozie.
I installed the thumb safety with the hammer strut elevated instead of along the frame. The hammer strut is now blocked by the safety from dropping into position on the frame. "Ok, that was new. I'll just pull the safety back off ..."
I'm sure you see the predicament. The hammer is also blocked from moving to full cock because of the hammer strut blocking its pivot. Without the hammer at full-cock, I can't remove the safety.
This has surely been done before, but I've never seen it. How do I fix what appears to me unfixable?
Tony