Anyone know where I can find a set of these please? There are two sets
and the output one has stopped working so I changed it for the
oscilloscope one. It screws out very easily and the contacts pull off
very easily as well.

They look pretty generic but I dont know how to identify who made them
or where I would find one? They werent actually made by Marantz were
they?

Or is there anything obvious I am missing on repairing the one which
is in there. One channel stopped working and I cant see any break in
the metalwork or anywhere the contacts would have stopped making
contact on it. (so I presumed something was broken inside, - in the
shaft somewhere inaccessible)