More out of curiosity than necessity for repair. I only have the user manual, block diagram, that shows reference to an 8 way relay for SOLO LED indicators and related signal routing. No sign of a relay - are a number of the ubiquitous 4560 dual op-amps tied together and used as gates ?
-- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list on
formatting link