I was asked to repair an ancient Selmer Clavioline, sort of a very early synthesizer. A few of the keys would stick and not play. Documented it here.
Great article on them here.
Probably 1955 if the Speaker is original which it looks to be. A valve in the unit is labelled '54 so it probably rolled out early 1955. Can't find any info on serial numbers although interestingly the hand written numbers on the chassis match that on the serial plate.
Glued loose key (top C) back on with epoxy resin.
Realigned key pins on keyboard.
Realigned key pins on "rocker" switches.
Checked for dry joints and cleaned keyboard unit.
Slightly sanded lower rear inside end of Bakelite front name panel to prevent lower keys from sticking.
Cleaned octave range slider and tremolo contacts.
Brushed dirt from case and cleaned dust from valves.
Cleaned the keyboard.
Repaired original non functioning power switch (was always stuck on).
Replaced melted polyester .001uF capacitor between output transformer and speaker with a ceramic equivalent.
Replaced mains cable with something more substantial (mains cable was not original).
Replaced what remained of vulcanised mains cable grip.
Cleaned valves and vacuumed out unit.
Rewired switch and fuse to be on the live mains side rather than the neutral side as this makes little sense now (I'm not sure it did in 1955 either!). This should be a little safer now as if the unit came into contact with an earth results would be unpredictable e.g. some or all of it would presumably become live to earth.
Notes: If you take off the two Bakelite covers on the ends of the keyboard there are trimming potentiometers which seem to set a high and low point for the tuner knobs on the side.