That's what i regard as conclusive then Rog! I have to admit that i've not tried to 'power-on' a 1xxx series without battery. It didn't work for me with an older unit, i think it was a 2x0 or maybe a 300 can't remember now. Nice tests, you've gone to some effort there and i'm sorry to cause you to do that to confirm your findings.
Shame about the outer surround cover, like me, they get quite brittle with age [they won't super-glue either btw, lol].