For a good explanation of this chassis see here:
http://www.thevalvepage.com/tv/marco...3da/vc73da.htm
This is the basically the same set as mine, but without the radio.
Sets such as these present a real challenge, after all if they were all easy we would soon get bored!
Having another set with the same chassis will be a great help, bits can be swapped out or compared. I wish I had more service info, but will have to make do with the Broadcaster sheet.
Mark