Well that one worked so here goes.

Sadly Alec's disks failed to kickstart the kn into life so after failing to find local dealerswho could fix it I contacted what was left of Technics at Panasonic, Bracknell who said they hadn't the facilities to repair it but gave me the name/phone number of someone who may be able to help. Technics mentioned that I may need a new motherboard, eproms etc and so did the prospective repairer. When I enquired about likely cost of all this - sharp intake of breath- and can't possibly say until we see it (understandable I s'pose) but if it's beyond repair it's seems it might be a bit expensive just to find this to be the case.
Am also pondering that with a now obsolete keyboard, and a disappeared provider of spares whether reluctantly go for another make, perhaps a Tyros 2 ?

I suppose the lesson behind all this is avoid all updates unless provided by the maker..
Peter