Michael W. Lynch
Do you have the Service manuals for this unit? If not, I would strongly advise you to cease working until you get the correct service manuals (at least get a digital copy). I have the paper manuals, which I prefer. I also have 3 of these scopes that I have repaired and the manual is essential to the process. These scopes are extremely complex and diagnosis or repair will be next to impossible without the manuals.
That being said, The analog section is almost identical to the 465B, so that helps. You can test for signals at or just prior to the deflection plates. The test points and wave forms are all shown in service manuals.
There is not any HV present on the deflection plates, as there is with the Cathode heater.
Good luck with your repairs.