The circuit is shown below and copied from the service manual. The 930 AC RMS volts on the power transformer secondary winding produces peak voltage of +/- 1315 volts (930 times 1.414 converts from RMS to peak volts). On the positive cycle, V1 is +1315 and V2 is approx 0 volts because the diodes at V2 are forward biased. So C1 is charged to 1315 volts at V1. On the negative cycle V2 is -1315 volts. Now current doesn't flow in the diodes at V2 because they are reverse biased. So the voltage at V2 is the voltage at V1 (-1315 volt) plus the voltage on C1 (another -1315 volts), so -2630 volts. This voltage charges C2-C3 through the diodes between V2 and V3. The voltage is filtered by C2-C3 & C4-C5 and the two 270 kohm resistors. Finally the two series 1000 volt zeners regulate the voltage down to 2000 volts.
However, if the scope runs, it should be worth at least $100 on Ebay, so it's still not a bad investment. I may still be able to find some replacement caps from another source.
For now, I've put the scope under the bench and will get to it after I get the parts.
Buying old equipment is kind of an adventure and a gamble. Usually the equipment is simple to troubleshoot and easy to fix, but occasionally, it's impossible to get replacement parts, or the parts cost more than the cost of the equipment. But that doesn't happen that often.