And now you see the difference between installation and repair.
Unless I missed it, I did not see the phrase "...and then I took out my meter and checked for metallic problems..."
A doctor will first check temperature, pulse rate, and blood pressure, regardless of the complaint, because experience shows that those three parameters can quickly be indicative of a patient's general condition.
The analogous readings by a professional telephone repairman are the results of testing with the KS meter. He will open the line(s) at the NID and look back towards the CO, and inward to the building, for metallic problems such as opens, shorts, escapes, grounds, crosses, and unbalances.
Eliminate those suspected problems, and then the real testing can take place. A parts replacer is not a repairman. In my career, I have followed around a herd of parts replacers.
As my old boss would say about his least favorite of them: "He couldn't find a cross in a church."
