I see on a recent thread there is mention of speaker damage on a G4 Quicksilver, namely separation of a rubber membrane and tears of the speaker cone. Which reminded me, I have a pair of G4 Cube speakers - model M7963 that are not aging well, and ideally need repair of the black cone material. (See photos below). Has anybody here attempted such a repair? If so, could you please share what was the precedure, the material used, and was the final result satisfactory?