My GTI has the 10 speaker audio system not the usual 8, and the drivers side Mid was not always working unless the volume was cranked up.....then it came alive. It was not the wiring to the door as that must be fine as the tweeter and bass speakers were fine.The Mid speaker was fine as all were replaced a couple of years ago so as a last resort I decided to swap out the factory crossover (the 10 wire, triangular module that the door have) and it workedI have full sound now and it also sounds better, so the original must have failed.
