@Lace,I've only just seen your reply, and thank you so much for it. It's good to have the name of a reliable 'fixer', I think I may need to use his services before very long.
My Featherweight doesn't seem to have wiring issues, it's more to do with the internal workings ie the shaft, and the feed dogs.
I found some more tutorials the other day, and took her out of her box to see if I could have another tinker. Unfortunately, I seem to have made matters worse, and now the shaft will only do a half turn.
I checked the timing, that seems OK, and the height of the feed dogs, but they still seem to be coming too far forward, and lifting the needle plate on the return.
It is now de-constructed on the sewing table, waiting for a rainy day, for me to either have another go, or pack it away again.
Jessie