Thanks again Gents,
I have gone with a used one as the price was very attractive and the labour I've been quoted by Darren Wood was very reasonable. Booked in for next Tuesday for a total cost which I can live with.
I realise the possibility of a false economy, but I trust the sellers word on this occasion and I will also honour the offer I made elsewhere - which will give me a spare one if need be.
Hopefully that will be it, but if not I can get DW to change it again and still be quids in.