Hi,
thanks for bringing that unit up, I'm a tape delay enthusiast and I didn't dont that unit.
I can't find a schematic or Service Manual for that unit in my sources, I'm sorry.
All those Evans delay units, tape or BBD, were also released with other brand names like Multivox and Ryan, might be others also.
You might try to find if the Super Echo ES-5 was released with the Multivox or Ryan brand and google that also for schematics or SM.
You can try to see the schematics available for other similar or from the same period Evans/Multivox tape delay units to see if there's similar parts of the circuit between units.
I was able to fix vintage gear with schematics from a different model but that had similar parts.
Try also to contact this fellow, he has Service Manuals for other Evans units and might know how you could source the docs for the ES-5:
http://estecho.com/2016/12/evans-super-echo-se-780/
By the way, whats the problem with your unit?
Normally those circuits are simple and might be easily fixable without a schematic.
Tell us whats going wrong and we might be able to help
regards