First step was knowing the insides. The scope has 7 tubes. 2 of them are 12AT6 (double triode), 3 are ECF80 (triode, pentode), a EZ80 (full wave rectifier) and the last one is the cathode ray tube, a D6 7-131 (equivalent to the D6 7-31 I presume).

It has a transformer with various windings, compatible with 115 and 230VAC changing some jumpers. It has 6.3V output for the heater of the board tubes and a dedicated 6.3V output for the cathode ray tube. It also has a 400V output with common winding and an 85V one. The scope has two silicon diodes for rectifying that voltage.

I first obtained the wiring for the transformer and the front and back pannel. The numbers you see are the numbers marked in the board for every wire connected to it, very convenient.

The more complicated step was getting the schematic. Now we can see how the scope is doing its magic.

With the schematics obtained, now it's time to see what could be happening. I can say for sure the tubes are OK. Changing the position of tubes of the same kind makes no difference at all, and all of the tubes look pretty neat. I also measured 440V out of the rectifier tube, so the ZF80 works. The cathode ray tube also looks okay. The focus and brightness "work" and there is some kind of deflection in both axis. 

I measured all filtering caps, at least capacitance, and they all looked ok. With (another) scope I could see no major AC component in the power rails. If it's not the power nor the tubes, maybe some other component went bad. 

Going to the point here. Every resistor and capacitor looked ok, maybe not in the tolerance limit, but there were not open circuits or short circuits. Every tube was getting its voltage.

There are two major problems: Y shift and X deflection. First one could be easier to get into, so that's the one I'll be focus on.