Thanks for the tip. A key puller couldn't budge the space bar, but a lever / wedge brought it part way up, but not disconnecting. The amount of force needing to pull it further seems alarming so I chickened out from trying further to fully disconnect the space bar.
I wondered whether there were any online videos showing anyone typing on their own display writer, to see how their space bar sounds. The following vid around the 22 second mark makes me suspect the sound I hear on mine is by design and not a sign of anything detached.
And a matter of getting used to unless I do some mod to dampen it.