Hi Jon. Many thanks. I actually think the build quality is perfectly good; cramped and awkward to work on, true, but definitely not poor quality. These sets must have sold in their millions and a lot of them have survived, so they can't be that bad!
As a postscript to this saga, I have discovered today that the 'Electric Handbag FT290 Group' on Yahoo has some good quality images of the component and print sides of the PCB that will hopefully save someone a lot of time in future repairs:
https://groups.yahoo.com/neo/groups/...bag/info?tab=s