First, many thanks for the replies, and the cool timing chain pic.

Finally just got back to the car after a couple months delay (!).

I drained the oil and removed the oil pan extension; no metal or bits of anything wrong in there.

I also removed the valve cover and tried turning the engine by hand again while looking at the chain and the cam. I swear to God I'm not crazy, and it WAS stuck, but this time I turned the engine about 5 complete revolutions of the bolt on the end of the crankshaft, and nothing stuck! The chain looked perfect as it went around the cam gear, and was snug with very little free play. I didn't check the cam timing yet, mostly because I don't know how and knowing me it will take about two hours for me to figure it out. But the cam timing was fine when I drove the car last, before the engine stuck, and I don't see any damage or anything I'd associate with it slipping.

Since it really WAS stuck, it doesn't seem like a good idea to just put it back together without finding what did it. but with everything looking fine, the only thing I can think of is to pull off all the chain covers and look inside. I suppose I could also put the starter back on and see how that works.

That's my story and I'm sticking to it. Ideas gratefully accepted!

thanks
Bruce S