Hey Dean ive installed the eprom in U3 with the adapter pcb

What type of EPROM is it? Can you peel the sticker back a bit and see if it says 2716 or 2764.

Also need to know the part number off the board and the part number for the CPU board specified in the manual. 

You could also try the EPROM in the PROM 1 and if that doesnt work PROM 2 socket without the adapter board.  Can you post a picture of the CPU board?