Any experience of gluing what seems to be a rubber dust cap back onto a polypropylene driver surface, more specifically, what glue works? The driver is a Scanspeak midrange/bass unit from a Sonus Faber Concertino which simply detached itself in the course of its modestly driven day to day life. [Concertino's sound wonderful but are put together out of pretty unexceptional and plasticky bits and pieces, that tend to, well, fall to bits and pieces rather like that other wonderful looking and sounding Italian marque, Alfa Romeo)