Final update to this thread,speakers arrived to day and fitted with no issues. All now working fine.
Would like to put on record my thanks and appreciation to Beverly and Andy at KEF, for accepting my comments in good faith, that I genuinely did not believe that I had overdriven the speakers and they had definitely not been thwacked. Andy
was particularly surprised after suggesting I get a subwoofer, when I informed him I already had an SVS PB2000 sub on my system.
Anyway, all now working fine, hopefully no more hiccups in the future. Would like to thank all for your valued comments Even the ("It must have been thwacked") ones. Though if I had knowingly damaged the speaker I would never have broadcast it on a thread. Also like to thank Matt Spandl at Acoustic Energy for recommending the glue ,which worked really well 😀.