We use an Alfatronic Mark IV Vacuum Tester, either when called in to look at specific problems, or as part of a routine investigation.

Below are some traces from testing we have done to demonstrate some of the findings, and the usefulness of the machine

This is the trace obtained from a milking plant which has a good, consistent, stable vacuum.
This trace shows lack of vacuum recovery after one, and then two claws are opened.  This indicates inadequate vacuum reserve.
This shows a good trace from a well-functioning dual pulsation system.
This trace shows distinct variation in teat end vacuum during milking - these fluctuations will almost certainly lead to increased likelihood of mastitis.