Just an update here, for reference really. I had been having problems with the input sockets. The bottom one was OK but the top wasnt working. Turns out it was a simple short from a bit of wire to earth. A little poking around and tidying did the trick. Now works OK. Both channels are fine. I had thought about completely re-doing the sockets, but that wasnt necessary
However, it shows the need for tidy lead dress and watching for "whiskers" of wire that can short out. Some of the distances that these whiskers need to jump are very small.
Barry refers to this type of problem in his testing procedure:
"By testing adjacent pins for continuity you can find shorts caused by wire 'whiskers' that are easily overlooked by the naked eye"
http://www.ampmaker.com/pp-18-initial-testing-1044-0.html
Anyway, all is fine now!
