Re: State of the copper?
For me: Missing twists in the pit at the front of the property meant that every time the pit filled with rainwater the capacitance of the line would change causing dropouts. An orphaned pairgain power feed from the next street over messed with the tech's test equipment, and my pair being only notionally wrapped about the connection posts, both in the bollard and at the green box, caused intermittent faults both when other people's lines were being worked on, or when the sun got a little too fierce.
I once had another sun related problem way back when I was a part of the Optus cable modem trial, there was a fault which only turned up on sunny afternoons for half an hour or so, and which of course was never there by the time the techs checked the line. A ping script run over the course of a few days showed the fault beginning almost exactly 4 minutes earlier every day. Since 4 minutes is the difference between the lengths of the sidereal and solar days, locating the fault had the techs literally chasing shadows.