Latest Report.
Went up to re-assemble the FW, and unlike yesterday, the bobbin assembly/shaft, went together beautifully.
With all my new knowledge, a maintenance book, and a video camera, I set to try my machine. Firstly I started by putting the needle plate back on without the screws, and rotated the handwheel by hand, with the stitch length set to the longest. It was lifting up at the front of the needle plate, and as the feed dogs moved back, the needle plate dropped down.
I then moved the stitch length lever right to the top, in reverse, and there was very little clatter.
I repeated the exercise with the motor running - noisier with the stitch lever on long than in reverse.
I think I have established that I have a Feed Dog Issue...
The feed dog is coming too far forward and needs adjusting... I don't know if I can manage that.
Just a smidge is all it needs...
Not sure how it happened. I'll now go and compose a hopefully coherent account to post on the SFUK on FB.
Thank you all so much for your invaluable help and advice.
Jessie