Thanks forum members for your offers of advice .
I received a call from Dave Sadler (manager) of Jack White Keyboards in Norwich . And the problem is solved . I pass on to you all, the following tip (just in case it happens to anyone else )
Fortunately it happened at home and not on a gig !!! (so someone up above does love me ) so to speak !!
1 Prog menu
2 controller
3 footswitch
4 my second foot switch is a single foot switch normally set to Rotary Slow/Fast
had defaulted to Glide setting .

A quick change and everything is back to normal !!!

it's a tip worth remembering !!

Regards .......Giovanni