Tektronix 7704A voltage multiplier DIY replacement

Some of theTEK 7000 series scopes use 21kV CRT high voltage to achieve high beam intensity.
During years of exploatation HV part become defect- prone.
The simple project contains PCB of 21kV voltage multiplier (similar to TEK 152-0493-00).
The components should have parameters:
Capacitors: 470pF...2,2nF /4kV
Diodes: Irms>50mA RMS; Vr>4kV; trr<100ns
The module must be well cleaned, dried in warm air, potted in urethane, silicone or epoxy.
Use well insulated HVcable.
It's better not to joke with 21kV.