I have finished testing the leakage current of the K71-7 470nF 250V capacitor at nominal voltage.
Voltage source: lab power supply B5-50
Current metter:
V7-49 electrometer.
Series resistor ~ 10GΩ KVM.
Test time ~ 9.5 h.
Leakage current is about 8pA.
Possibly, the leak current can be even lower, but 10GOm resistor too small in order to get rid of the noise rise in the lower measuring range.
I am attaching a raw data file.