I am sorry if this was mentioned already - just did a quick scan through the post...
I switched to LED displays in an Eight Ball with the same type of issue. The end result was a broken wire in the harness (in series) between the displays.
Checked continuity between each display one at a time to diagnose.
I also might suggest nice shiny new trifurcon connector pins in ALL 5 of the 20 pin connectors to go with those nice new displays!
-scott