Well, I've replaced the cap and broke the pot down and cleaned it with alcohol (it was just a little dirty). I tested the pot and only got 462k ohm. The result is the same, around +5.7 on the pot output.
I bought another 400 from ebay and when it comes in I'll try out the CPU board to see what I can do.
Very frustrating! But, thanks everyone for the help and instruction.