SO I went to Marvin 3 guide - it advised to remove and re-seat the short flat strap between the 2 boards - I did that, and now........
Are you referring to the ribbon cable between the CPU and the Driver board? If so, then it can cause strange problems, but as it is address and data for lamps, coils, GI and so on, you are more likely to see other parts of the machine misbehaving and not just one lamp.
It is possible that the ribbon cable is now causing lamp columns 1 and 8 to act as one. I would remove and re-fit the ribbon cable again (and even turn it around) and see if the prob goes away or changes.
Back to the original lamp prob...
What does the diode measure (both measurements)?
The diode may be "out of spec" but not 'short' or 'open', causing the "ghosting" you are seeing. (By they way - 'short' means zero ohms, and 'open' means no reading at all, like the multimeter probes are not touching anything)
And what is the other diode you've found reading? Again, it might be out of spec as well...
