I have phoned a shop in Worcester - thanks
@fajita I have had a great deal of very useful advice over the phone.
He certainly seemed to know what he was talking about and although they are booked solid for service/repair till after Christmas he has made several suggestions for me to try which I will do today.
He suggested it may be the walking foot which I was thinking it may be when I was fiddling yesterday. They have had problems with some of them
Fingers crossed everyone - oh and I have filled in a booking form for a service