Hi Derek, yes i tried the 6821, fitted a brand new one as well as swapping it with the other one on the board. I also replaced the 470pF ceramic caps on the digit select outputs from the 6821 ic, to no avail. The connector seemed to be ok, havent looked at it in great detail as yet, and there is no acid damage on the board at all to speak of.

I DID also change a couple of the other ICs the 4502 which fixed the lamp problems it had and a couple of others, cant remember the board reference numbers, and the pdf copy of the schematic i have here is hard to read the component values  Ian has the full manual for his game which has come in handy so far for sorting the other issues it had.