That's the trouble with so much modern kit, Laiq ... the manuals place so many obstacles in the way of (what we might call) a "generic"* approach to testing.
All very well perhaps if you're based in a hospital, with only one line of ESU's to support. But what about those of us who may encounter various types, from various manufacturers, and of various
vintage?Well, one way would be to have to hand every bit of test equipment known to man ... but failing that, I would suggest reverting to "first principles".
In the case of ESU's (of any type) I would suggest the following approach with regards to Output:-
Waveforms across an appropriate load! And work up your own procedure(s), using whatever test equipment you have to hand, and retain good records (for comparison next time).
In theory, any decent ESU analyser should be able to be pressed into service. Those older ones are basically just heavy load resistors, after all (as are the later ones ... that's why they're so hefty)! And the one you've got there is a good old one, is it not?
With regards to testing the various "clever" (and some not so clever) return electrode circuits, with alarm trigger levels and such ... well you just have to improvise a bit there, I'm afraid.
Good luck, Mate. Be sure to let us know how you get on.

But what's the big deal about using
this thing? "High currents transformed to pleasant scope input levels" ... there must be another way (because there always is)! If the manual only talks about current measurements (?), then that sounds like a return to good old Ohm's Law to me!
Lastly, check out
this .pdf.
As an aside (if I may) many donated ESU's fail to get used due to what are often "minor" faults - and lack of local know-how when it comes to checking them out. Take a look at
this.
*
Shade-tree?