That reminds me of a case of trouble I had one time where a customers phone line went out of service when a service guy climbed their pole and hooked up a new line. Every time I opened the service box on the pole the line came clear and worked. Every time I shut the door it went grounded and went out of service again. Come to find out a month later this was reported to us as a manufacturing defect where the lock on the door when turned and grounded out the terminal 38. My customer was on terminal 38. I found this same case of trouble over the years many times as this was a very common box and we installed thousands of them over the years.