Machine stopped abruptly right after start of final rinse drain, about the time that bulk water was out. It had been knocking during spin. Visually it did not seem unduly out of balance at the time, although one heavy towel may have been producing some unbalance. Took the wet clothing out; timer did not proceed to the spin phase.
Re-ran the machine from the start without clothing – it filled and agitated, drained and spun. During this phase I checked the door switch – it seems to be doing what I expected, not permitting the machine to run with door open, and allowing it to restart after a seeming "time-out" after closing the door.
However, even with no clothes in spin basket, during the first spin cycle it knocked – even pounded – as if badly out of balance. It stopped after what seemed to be about the right time for extracting water had there been clothes in it. Then the timer stopped before entering the fill cycle for rinse cycle and did not proceed further.
I bought the washer five years ago with the condo, so not sure about age – at least 6 or 7 years, but may well be over 10.