On Wednesday, 5 August 2020 13:11:56 UTC+1, T i m wrote:

So, it's possible this electromagnetic clutch-brake has been marginal
for some time and was pushed past the point of functionality
yesterday.

The fact that the three screws that hold the clutch-brake together
were all lose suggest someone may have done that to allow some 'slack'
in the assembly.

The friction disk smells like Bakelite and given it won't ever release
mechanically (manual override) and that mech is working, I'm wondering
if the friction disk may have swollen due to damp or somesuch?

Bottom line, I can either try to skim the disk (might be able to mount
it on the lathe) or space the mech out slightly so that in the
manually 'opened' position the disk floats freely (even if it doesn't
when it should be electrically activated).

Cheers, T i m

are they not cheaply available used on ebay?