Hi Corby,
Nice SA!
I also did find the 610B manual, but curious how close the "A" version of the SA to the "B" version is?
I could not find the part number of the CRT in the part list, but that would be a way to find the operating voltages to the CRT, by looking up the datasheet of the CRT.
Possibly you could identify the CRT from the actual unit and go from there.
Also, a first step would be to check the supply voltages, if they in spec, and without ripple.
Good luck, Peter