I wish they could make something electronic that could be reliable. Oh-reliable, that would be the good old mercury manometer. I know a lot of sites ban said device, but carrying it in inside your pocket does work most times as it should only take a couple of minutes to check the vacuum. It don't run on batteries which run down, hence trying like an insane scientist to get the same reading twice. Anyway, I think I just gave 3 cents instead of 2 cents worth there.
We aren't service engineers, we are service re-engineers!! Work is what you make it, have fun.....