Well today I was charged with taking out an old plant from an old sandwich cooler. So I removed the plant and be for cleaning it up I was told to check it. So I pulled a vac (The unit had leaked dry) and it actually held just fine, So I tested and noticed pressure wasn't holding well (But yet it held a vac!) So I went through and tested each part with soap water and BANG found the sight Glass bubbling away. I never seen this be for, How often does that occur?

I swapped out with a new sight glass and F/D and it's purring away, but was rather curious that a sight glass was leaking!