Yi2 Qian1 Jia1 Brewery Equipment Ltd Pomace Press Sold on ebay
This video is showing how the head of the Hydraulic Jack leaks oil when you open the pressure gauge. After all, since the Jack doesn't go down immediately when you release pressure, one can only open it for a few minutes, which then results in mechanical oil leaking out.
Thus if you only release pressure for a short period of time, you fail. When you release for a long period of time, you fail. This situation can be described by "Catch 22", or in Chinese 動輒得咎。