First of all, the ink should come from the pipe on this side of the main ink tank:







This is the main flow of ink.
Then, look at this pressure sensor:



It comes directly from the ink path of the ink supply, that is, the ink behind the main filter. As soon as the viscosity valve is opened, the ink will enter the viscometer, and then the viscometer will top the small beads to the highest point and then fall. How long will it take to return to the lowest point, and then measure this value.