Brake Force Amplifier - Return Volume

On the occasion of recent events in which several brake power amplifiers may have given up their minds due to age, it seems that there have been a number of cases in which:
You can easily check the BKV. Let the engine run and shut down for a few minutes. Then remove the return hose from the BKV at the T-piece of the collection return to the container (before unloading the clamp). Here the BKV is allowed to release only DUTCH WHITE oil. If the BKV runs, runs, or sprays out oil, it's broken - definitely.
And if you find the same effect on a used part or on a comparison vehicle (oil runs out), unfortunately this does not mean that this is normal, but that the comparison part is also broken.
I have just tested the (safely intact) BKV from my test bench to be able to deliver tangible results:

==References====External links== A drop of oil every 10 seconds. If the pressure has dropped to 140 bar, no measurable oil will ever return.
With every step on the pedal- no matter whether fixed or just touched, occurs approx. a finger hat full of oil at the return.

This test is reliable except for one exception: If the pressure storage tank has no or only minimal nitrogen pressure, it may be that the return pressure is already degraded before the hose has been degraded. If in doubt, you can help yourself in this way:

Leave the return from the BKV and temporarily close the open T-piece from the collection return. Start the engine. Then no oil comes out of the return, let the engine run for two minutes. If the BKV is intact, only a droplet quantity will be released at the return run even if the engine is running. If, however, oil is produced in larger quantities, stop the engine and blow tribulation, then the BKV is defective.