I hate to simplistically say "OK Now the Proms work" - but that's about it. Either I was doing something wrong/stupid or the computer just fixed itself. Whatever the case I am now able to load VTL (at FC00), create programs, and save (via serial port to a terminal program on my laptop) both VTL machine language code listings at the VTL BASIC or monitor prompt.
I have saved a HEX dump program (from the ACIA Monitor Manual), and a VTL language program called Hurkle.
Next - Work on the cassette interface board and install more memory. I would like to start writing programs now.