Thanks everyone - there's a lot here that I have little understanding of!
Bear with me, and I will try to get my head around it.
In the meantime, I am going back to basics - I have ordered a load of new electrolytics for the power supply, and will also replace any that are lurking elsewhere - I think 35+ years is asking a lot of these components.
Chris, Ah, ok , more Warsaw than Cambridge then
The machine is a bit heavy for hand luggage
Power supply parts are at the post office, so hopefully I can get that part finished off Friday evening, then carry out some of the testing that has been suggested.
Really appreciate all the trouble everyone is going to.
Sean