I have a pair of B&W 602 3's as my dronts. Since yeterday, I am noticing a strange problem. The tweeter of the left speaker stops producing any sound from time to time. One bang on top of the speaker kicks it into action. Anyone has had this problem? There were no knocks or anything like that,and why should the bang on the speaker kick it into action once again? It is within warranty, so should I ring B&W? How is the service from them? Do they replace speakers? It was bought only in September/October last year.