O.K. __ I still don’t know what went wrong yesterday, but I am much happier now, and really rather impressed with the Bambu Handy App
I switched the printer on, adjusted nothing, and retired to another room
Then searched for something reasonably small and familiar to print … and found a 1/4 20 camera screw
Having simply confirmed a few details of the printer, filament, and plate, I then sent it to print [no physical interaction with the printer]
Twenty minutes later I collected this:
.

.

.
It’s not perfect, but it’s very useable
MichaelG.